Category Archives: University of California, Berkeley


Bacterial ‘aphrodisiac’ can trigger protist sex swarms

To the surprise of scientists, bacteria can act as an aphrodisiac for the one-celled marine organisms that are the closest living relatives of all animals.

This is the first known example of bacteria triggering mating in a eukaryote, a group that includes all plants and animals.

The organisms, protists called choanoflagellates, eat bacteria and serve as a source of food for small ocean animals like krill.

Several years ago, the lab Nicole King, a professor of molecular and cell biology at the University of California, Berkeley, and Howard Hughes Medical Institute investigator, discovered that certain bacteria make these one-celled choanoflagellates (a.k.a. choanos) develop into multicellular colonies.

The new discovery suggests that choanos “eavesdrop” on bacteria to make sense of their environment and regulate their life history.

The discovery may help reveal how humans and other animals evolved from single-celled organisms over the last 600 million years.

multicellular rosettes
A different bacterium induces the development of multicellular rosettes, which arise through multiple divisions of a single founding cell. (Credit: Arielle Woznica/UC Berkeley)

In this case, the bioluminescent marine bacterium Vibrio fischeri triggers the choanoflagellate Salpingoeca rosetta to swarm and mate. Mating is sometimes a response to a changing environment.

“A lot of evolutionary theory favors the idea that mating happens when conditions are stressful, because you need to reshuffle the deck. With sexual reproduction, you will hopefully get a new combination of gene alleles that is more fit for whatever is coming down the pike,” King says.

“Bacteria are very good at integrating a lot of information about the environment, as different species of bacteria have different nutrient requirements. Choanos may be using bacteria as a proxy for environmental conditions, or live indicators for when its time to get ready for good or bad times,” she says.

Mating among choanoflagellates has been a mystery—even whether choanos engaged in sexual reproduction—until her team discovered in 2013 that starvation could trigger mating, although only a small percentage of cells would mate. The new study shows that Vibrio bacteria elicit a much more rapid response, with large percentages of cells mating within hours.

“Choanoflagellates have a lot of flexibility in their life history. They can go on and on being asexual, but now we’ve found that they can also be sexual, and that the switch to sexuality is induced by a bacterial cue within an hour after exposure,” says King.

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The new discovery suggests that other creatures, including some that have been difficult to study in the lab because they fail to mate, may need a little bacterial aphrodisiac to get it on.

“One possibility is that these animals need particular cues from environmental bacteria that are not being provided in the lab,” she says.

After UC Berkeley graduate student Arielle Woznica discovered that these bacteria initiated swarming, they collaborated with Jon Clardy’s lab at Harvard Medical School to track down the trigger: a protein the bacteria secrete constantly, which they dubbed EroS.

They showed that EroS is a chondroitinase, an enzyme that degrades a specific type of sulfated molecule found in the extracellular matrix of S. rosetta that was previously thought to be exclusive to animals. They also found that if this enzymatic function was inhibited, swarming did not occur, and that chondroitinases from other aquatic bacteria reproduced the aphrodisiacal effects. As the teams investigate how EroS works, they’re continuing to explore the interactions between bacteria and choanoflagellates.

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As for implications for animals like humans and their bacterial partners, the so-called microbiome, King says that “we hope that by studying choanos, which are really simple, that we can identify key molecules and then go into the more complex environment of the gut microbiome, for instance, and see whether some of these molecules matter in that context as well.”

“I think by demonstrating a new type of bacteria-induced behavior, we may inspire others to look in the systems they study and see if they might have missed that bacteria play a role there as well,” says co-first author Joseph Gerdt, a postdoctoral researcher at Harvard Medical School.

The National Institutes of Health funded the work, which appears in the journal Cell.

Source: UC Berkeley

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Squirrels use ‘chunking’ to organize their nuts

Fox squirrels are a lot more organized than we thought—storing their stashes of nuts by variety, quality, and possibly even by preference.

A new study is the first to show evidence that squirrels arrange their bounty—at least 3,000 to 10,000 nuts a year—using “chunking,” a cognitive strategy in which people and other animals organize spatial, linguistic, numeric, or other information into smaller more manageable collections, such as subfolders on a computer.

“This is the first demonstration of chunking in a scatter-hoarding animal, and also suggests that squirrels use flexible strategies to store food depending on how they acquire food,” says Mikel Delgado, a postdoctoral researcher at the University of California, Berkeley, and lead author of the study in Royal Society Open Science.

Presumably, sophisticated caching techniques maximize the squirrels’ ability to remember where they’ve stored their most prized treats while at the same time hiding them from potential pilferers.

“Squirrels may use chunking the same way you put away your groceries,” says senior author Lucia Jacobs, a professor of psychology.

“You might put fruit on one shelf and vegetables on another. Then, when you’re looking for an onion, you only have to look in one place, not every shelf in the kitchen.”

Over a two-year period, the research team tracked the caching patterns of 45 male and female fox squirrels as the reddish gray, bushy-tailed rodents buried almonds, pecans, hazelnuts, and walnuts in various wooded locations.

The study used combinations of locations and nut sequences on various groups of fox squirrels.

In one experiment, for example, each of the squirrels were fed 16 nuts, one after another, under two separate conditions: Some were fed at the locale where they had cached the previous nut fed to them while others were fed at one central location, to which they would need to return if they wanted another nut.

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Some squirrels were given 16 nuts in rows of four, say, almonds followed by pecans, followed by hazelnuts, and then walnuts, while others received 16 nuts in random order.

Researchers used hand-held GPS navigators to track the squirrels from their starting location to their caching location, then mapped the distribution of nut types and caching locations to detect patterns.

Squirrels who foraged at a single location frequently organized their caches by nut species, returning to, say, the almond area, if that was the type of nut they were gathering, and keeping each category of nut that they buried separate. Meanwhile, the squirrels foraging in multiple locations deliberately avoided caching in areas where they had already buried nuts, rather than organizing nuts by type.

“These observations suggest that when lacking the cognitive anchor of a central food source, fox squirrels utilize a different and perhaps simpler heuristic (problem-solving approach) to simply avoid the areas where they had previously cached,” the authors write.

Source: UC Berkeley

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We have 27 kinds of emotion, not just 6

A new study has pinpointed 27 separate categories of human emotions, challenging an old assumption in psychology that most emotions can be categorized as happiness, sadness, anger, surprise, fear, or disgust.

Using novel statistical models to analyze the responses of more than 800 men and women to over 2,000 emotionally evocative video clips, researchers identified the 27 distinct categories of emotion and created a multidimensional, interactive map to show how they’re connected.

“Emotional experiences are so much richer and more nuanced than previously thought.”

“We found that 27 distinct dimensions, not six, were necessary to account for the way hundreds of people reliably reported feeling in response to each video,” says study senior author Dacher Keltner, a psychology professor at the University of California, Berkeley.

Moreover, in contrast to the notion that each emotional state is an island, the study found that “there are smooth gradients of emotion between, say, awe and peacefulness, horror and sadness, and amusement and adoration,” Keltner says.

“We don’t get finite clusters of emotions in the map because everything is interconnected,” says study lead author Alan Cowen, a doctoral student in neuroscience at the university. “Emotional experiences are so much richer and more nuanced than previously thought.”

“Our hope is that our findings will help other scientists and engineers more precisely capture the emotional states that underlie moods, brain activity, and expressive signals, leading to improved psychiatric treatments, an understanding of the brain basis of emotion and technology responsive to our emotional needs,” he adds.

Check out the interactive emotion map. (Warning: Some of the map’s video clips may be inappropriate or upsetting)

For the study, a demographically diverse group of 853 men and women went online to view a random sampling of silent 5- to-10-second videos intended to evoke a broad range of emotions.

Themes from the 2,185 video clips—collected from various online sources for the study—included births and babies, weddings and proposals, death and suffering, spiders and snakes, physical pratfalls and risky stunts, sexual acts, natural disasters, wondrous nature, and awkward handshakes.

Three separate groups of study participants watched sequences of videos, and, after viewing each clip, completed a reporting task. The first group freely reported their emotional responses to each of 30 video clips.

“Their responses reflected a rich and nuanced array of emotional states, ranging from nostalgia to feeling ‘grossed out,’” Cowen says.

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The second group ranked each video according to how strongly it made them feel admiration, adoration, aesthetic appreciation, amusement, anger, anxiety, awe, awkwardness, boredom, calmness, confusion, contempt, craving, disappointment, disgust, empathic pain, entrancement, envy, excitement, fear, guilt, horror, interest, joy, nostalgia, pride, relief, romance, sadness, satisfaction, sexual desire, surprise, sympathy, and triumph.

“We sought to shed light on the full palette of emotions that color our inner world.”

Here, the experimenters found that participants converged on similar responses, with more than half of the viewers reporting the same category of emotion for each video.

The final cohort rated their emotional responses on a scale of 1 to 9 to each of a dozen videos based on such dichotomies as positive versus negative, excitement versus calmness, and dominance versus submissiveness. Researchers were able to predict how participants would score the videos based on how previous participants had assessed the emotions the videos elicited.

Overall, the results showed that study participants generally shared the same or similar emotional responses to each of the videos, providing a wealth of data that allowed researchers to identify 27 distinct categories of emotion.

Through statistical modeling and visualization techniques, the researchers organized the emotional responses to each video into a semantic atlas of human emotions. On the map, each of the 27 distinct categories of emotion corresponds to a particular color.

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“We sought to shed light on the full palette of emotions that color our inner world,” Cowen says.

Their findings appear in the Proceedings of the National Academy of Sciences.

Source: UC Berkeley

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Cognition tends to peak later if you have more degrees

A new study suggests that higher levels of education are tied to later ages of peak cognitive functioning.

The study, which appears in the journal PLOS ONE, examined relationships between educational attainment, cognitive performance, and learning in order to quantify the cumulative effect of attending school.

age of peak cognitive performance chart
This chart shows the age at which cognitive performance peaks align with the average age of completion of educational degrees by participants in a study of education and cognition. Colored points show the median age of maximum performance while gray, dotted lines represent the age range of peak performance, and colored squares show the median age of typical graduation for each education level. (Credit: PLOS ONE via UC Berkeley)

Its findings suggest that higher levels of education may help stave off age-related cognitive decline. In addition, the team found that education didn’t have a large impact on novel learning, or learning something new at various points in time.

Conventional wisdom has long accepted that higher education is likely to boost incomes and helps prepare individuals for a workplace with often-changing skill sets. Yet fewer than 40 percent of adults in the United States are expected to graduate from college in their lifetimes, and the percentage declines for more advanced degrees.

Until now, research has been inconclusive about the cognitive impacts of higher education and whether the quantity of schooling can influence the acquisition and maintenance of cognitive skills over time.

“…schooling doesn’t merely impart knowledge—it also provides the opportunity to sharpen core cognitive skills…”

Bunge and her team say higher levels of education are strong predictors of better cognitive performance across the 15- to 60-year-old age range of their study participants, and appear to boost performance more in areas such as reasoning than in terms of processing speed.

The study’s findings are consistent with prior evidence that the brain adapts in response to challenges, a phenomenon called “experience-dependent brain plasticity.” Based on the principles of plasticity, the authors predicted improvements in cognitive skills that are repeatedly taxed in demanding, cognitively engaging coursework.

Differences in performance were small for test subjects with a bachelor’s degree compared to those with a high school diploma, and moderate for those with doctorates compared to those with only some high school education.

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The researchers note that people from lower educational backgrounds learned novel tasks nearly as well as those from higher ones.

“The fact that the cognitive tests were not similar to what is learned in school is a strength of the study: It speaks to the idea that schooling doesn’t merely impart knowledge—it also provides the opportunity to sharpen core cognitive skills,” says Bunge.

The researchers analyzed anonymized data collected from around 196,000 Lumosity subscribers in the United States, Canada, and Australia who came from a range of educational attainment and diverse backgrounds. Participants complete eight behavioral assessments of executive functioning and reasoning that are unrelated to educational curricula as part of their subscription.

The research team also looked closely at a subset of nearly 70,000 subscribers who finished Lumosity’s behavioral assessments a second time after about 100 days of additional cognitive training. Testing before and after the assessments measured cognitive performance in areas such as working memory, thinking quickly, responding flexibly to task goals, and both verbal and non-verbal reasoning.

“Given the size and wide age range of our sample, it was possible to test whether these age effects are influenced by education—and, importantly, to determine how the cognitive effects of educational attainment differ across the lifespan, as one’s experience with formal education recedes into the past and is supplanted by other life experiences,” the team writes.

Bunge says that collaborating with Lumosity was an opportunity to analyze data from a large number of participants—an anonymized dataset that would have taken a lifetime to collect in a laboratory.

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Additional researchers contributing to the paper are from the University of California, Berkeley and Lumos Lab.

Source: UC Berkeley

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Common pesticide may cause lung problems in kids

The most heavily used pesticide in California, elemental sulfur, may harm the respiratory health of children who live near farms that use it, new research suggests.

In a study of children in the Salinas Valley’s agricultural community, researchers found significant associations between elemental sulfur use and poorer respiratory health.

“We need to better understand how people are exposed to sulfur used in agriculture and how to mitigate exposures.”

The study, which appears in the journal Environmental Health Perspectives, linked reduced lung function, more asthma-related symptoms, and higher asthma medication use in children living about a half-mile or less from recent elemental sulfur applications compared to unexposed children.

The Environmental Protection Agency generally considers elemental sulfur as safe for the environment and human health, but previous studies have shown that it is a respiratory irritant to exposed farmworkers.

Elemental sulfur’s effect on residential populations, especially children, living near treated fields has not previously been studied despite the chemical’s widespread use and potential to drift from the fields where it is applied. This study is the first to link agricultural use of sulfur with poorer respiratory health in children living nearby.

Elemental sulfur is allowed for use on conventional and organic crops to control fungus and other pests and is very important to both systems. It is the most heavily used agricultural pesticide in California and Europe. In California alone, more than 21 million kilograms of elemental sulfur were applied in agriculture in 2013.

“Sulfur is widely used because it is effective and low in toxicity to people. It is naturally present in our food and soil and is part of normal human biochemistry, but breathing in sulfur dust can irritate airways and cause coughing,” says coauthor Asa Bradman, associate director of the Center for Environmental Research and Children’s Health at the University of California, Berkeley’s School of Public Health.

“We need to better understand how people are exposed to sulfur used in agriculture and how to mitigate exposures. Formulations using wettable powders could be a solution,” she says.

For the study, the research team examined associations between lung function and asthma-related respiratory symptoms in hundreds of children living near fields where sulfur had been applied.

The children were participants in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, a longitudinal birth cohort that is a partnership between UC Berkeley and the Salinas Valley community.

CHAMACOS is the longest running longitudinal birth cohort study of pesticides and other environmental exposures among children living in an agricultural community. The cohort participants were primarily born to families of immigrant farmworker families.

The study found several associations between poorer respiratory health and nearby elemental sulfur use. A 10-fold increase in the estimated amount of sulfur used within 1 kilometer of a child’s residence during the year prior to pulmonary evaluation was associated with a 3.5-fold increased odds in asthma medication usage and a two-fold increased odds in respiratory symptoms such as wheezing and shortness of breath.

Kids exposed to pesticides have smaller lungs

The study also found that each 10-fold increase in the amount of elemental sulfur applied in the previous 12 months within a 1-kilometer radius of the home was associated with an average decrease of 143 milliliters per second (mL/s) in the maximal amount of air that the 7-year-old children could forcefully exhale in one second.

For comparison, research has shown that exposure to maternal cigarette smoke is associated with a decrease of 101 mL/s after five years of exposure.

The researchers used regression models to control for maternal smoking during pregnancy, season of birth, particulate matter air pollution, breast feeding duration, child’s sex and age, height, technician, and other covariates.

“This study provides the first data consistent with anecdotal reports of farmworkers and shows that residents, in this case, children, living near fields may be more likely to have respiratory problems from nearby agricultural sulfur applications,” says senior author Brenda Eskenazi, a professor at the School of Public Health.

Given elemental sulfur’s widespread use worldwide, the study authors call urgently for more research to confirm these findings and possible changes in regulations and application methods to limit impacts of sulfur use on respiratory health.

The National Institute of Environmental Health Sciences and the EPA funded the research. The Environment and Health Fund in Israel supported Rachel Raanan, a University of California, Berkeley postdoctoral fellow and the study’s lead author.

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Research protocols were approved by the UC Berkeley Committee for the Protection of Human Subjects.

Source: UC Berkeley

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Specialty mental health probation means fewer rearrests

Placing people with mental illness who have been arrested on “specialty mental health probation” could lead to fewer rearrests than placing them on traditional probation, a new study suggests.

“Specialty probation holds substantial promise as a method for reducing mass incarceration for people with mental illness…”

Each year, some two million people with schizophrenia, bipolar disorder, and other mental illnesses are arrested for various crimes, inadvertently turning the US correctional system into the nation’s primary provider of inpatient psychiatric care. The new study, however, may offer a partial solution.

Researchers studied the supervision and outcomes of 359 offenders with mental illness, comparing those who had been placed on traditional probation against those on “specialty mental health probation,” a program in which probation officers with mental health expertise use a more individualized, treatment-oriented approach.

Their findings, published today in the Journal of the American Medical Association – Psychiatry, show that 52 percent of traditional probationers were rearrested over a two-year follow-up period, compared to 29 percent of specialty probationers.

“We found that specialty officers had better relationships with probationers, participated more in probationers’ treatment, and relied more on positive compliance strategies than traditional officers,” says study lead author Jennifer Skeem, a professor of social welfare and of public policy at the University of California, Berkeley.

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Skeem and fellow researchers launched the study in 2006, recruiting probationers with mental illnesses in two demographically similar urban areas of Texas and California. About half of offenders were placed on specialty probation while the other half were on regular probation.

For the first year of the study, researchers interviewed probationers and their officers three times. Next, they obtained FBI arrest records to assess which probationers had reoffended in up to a five-year period. All probationers were followed for at least two years.

In their analysis, researchers found that the odds of rearrest for people on regular probation were more than two-and-a-half times higher than for those on special probation at two years, and that the benefits of specialty probation lasted for up to five years.

“Specialty probation holds substantial promise as a method for reducing mass incarceration for people with mental illness,” Skeem says.

Moreover, she adds, “prisons and jails spend two to three times more money on offenders with mental illness but rarely see improvements in public safety. This is one of the reasons that more than 375 US counties have joined the Stepping Up Initiative, a national effort to reduce the number of people with mental illness in jails.”

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Additional coauthors of the study are from the University of Cincinnati, Ohio, and UC Berkeley.

Source: UC Berkeley

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Fighting negative emotions can make you feel worse

Embracing negative emotions can make you feel better, while pressure to be positive can actually make you feel worse, new research suggests.

“…if you’re constantly judging your emotions, the negativity can pile up.”

“We found that people who habitually accept their negative emotions experience fewer negative emotions, which adds up to better psychological health,” says study senior author Iris Mauss, an associate professor of psychology at University of California, Berkeley.

At this point, researchers can only speculate on why accepting your joyless emotions can defuse them, like dark clouds passing swiftly in front of the sun and out of sight.

“Maybe if you have an accepting attitude toward negative emotions, you’re not giving them as much attention,” Mauss says. “And perhaps, if you’re constantly judging your emotions, the negativity can pile up.”

The study, which appears in the Journal of Personality and Social Psychology, tested the link between emotional acceptance and psychological health in more than 1,300 adults in the San Francisco Bay Area and the Denver, Colorado, metropolitan area.

The results suggest that people who commonly resist acknowledging their darkest emotions, or judge them harshly, can end up feeling more psychologically stressed.

By contrast, those who generally allow such bleak feelings as sadness, disappointment, and resentment to run their course reported fewer mood disorder symptoms than those who critique them or push them away, even after six months.

“It turns out that how we approach our own negative emotional reactions is really important for our overall well-being,” says study lead author Brett Ford, an assistant professor of psychology at the University of Toronto. “People who accept these emotions without judging or trying to change them are able to cope with their stress more successfully.”

Three separate studies were conducted on various groups both in the lab and online, and factored in age, gender, socio-economic status, and other demographic variables.

“It’s easier to have an accepting attitude if you lead a pampered life, which is why we ruled out socio-economic status and major life stressors that could bias the results,” Mauss says.

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In the first study, more than 1,000 participants filled out surveys rating how strongly they agreed with such statements as “I tell myself I shouldn’t be feeling the way that I’m feeling.” Those who, as a rule, did not feel bad about feeling bad showed higher levels of well-being than their less accepting peers.

Then, in a laboratory setting, more than 150 participants were tasked with delivering a three-minute videotaped speech to a panel of judges as part of a mock job application, touting their communication skills and other relevant qualifications. They were given two minutes to prepare.

After completing the task, participants rated their emotions about the ordeal. As expected, the group that typically avoids negative feelings reported more distress than their more accepting peers.

In the final study, more than 200 people journaled about their most taxing experiences over a two-week period. When surveyed about their psychological health six months later, the diarists who typically avoided negative emotions reported more mood disorder symptoms than their nonjudgmental peers.

Next, researchers plan to look into such factors as culture and upbringing to better understand why some people are more accepting of emotional ups and downs than others.

“By asking parents about their attitudes about their children’s emotions, we may be able to predict how their children feel about their emotions, and how that might affect their children’s mental health,” Mauss says.

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In addition to Mauss and Ford, additional coauthors of the study are from UC Berkeley and Northwestern University. The National Institute on Aging funded the research.

Source: UC Berkeley

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Climate change in India causes spike in suicides

There have been more than 59,000 suicides in India in the past 30 years. Now, experts say failing harvests that push farmers into poverty are likely the key culprits.

A new study in the Proceedings of the National Academy of Sciences shows that warming a single day by 1 degree Celsius (1.8 degrees Fahrenheit) during India’s agricultural growing season leads to roughly 65 suicides across the country, whenever that day’s temperature is above 20 degrees Celsius (68 degrees Fahrenheit). Warming a day by 5 degrees Celsius has five times that effect.

While high temperatures and low rainfall during the growing season have a substantial effect on annual suicide rates, similar events have no effect on suicide rates during the off-season, when few crops are grown, suggesting that agriculture is the critical link.

map of suicides in India
Darker red colors in the map of India above indicate more suicides due to climate changes that have already occurred since 1980 (Credit: Carleton in PNAS.)

The findings help explain India’s evolving suicide epidemic, where suicide rates have nearly doubled since 1980 and claim more than 130,000 lives each year—and indicate that 7 percent of the upward trend can be attributed to warming that has been linked to human activity.

More than 75 percent of the world’s suicides are believed to occur in developing countries, with one-fifth of those in India alone. But there has been little hard evidence to help explain why poor populations are so at risk.

“It was both shocking and heartbreaking to see that thousands of people face such bleak conditions that they are driven to harm themselves,” says Tamma Carleton, a doctoral fellow at the Global Policy Laboratory and a PhD candidate in agriculture and resource economics at the University of California, Berkeley. “But learning that the desperation is economic means that we can do something about this. The right policies could save thousands.”

“The tragedy is unfolding today. This is not a problem for future generations. This is our problem, right now.”

The study demonstrates that warming—forecast to reach 3 degrees Celsius by 2050—is already taking a toll on Indian society. Using methods that she developed in a previous paper published in the journal Science, Carleton projects that today’s suicide rate will only rise as temperatures continue to warm.

Optimists often suggest that society will adapt to warming. But Carleton searched for evidence that communities acclimatize to high temperatures, or become more resilient as they get richer, and found none in the data.

“Without interventions that help families adapt to a warmer climate, it’s likely we will see a rising number of lives lost to suicide as climate change worsens in India,” she says.

Carleton says she hopes her work will help people better understand the human cost of climate change, as well as inform suicide prevention policy in India and other developing countries.

“The tragedy is unfolding today. This is not a problem for future generations. This is our problem, right now.”

Debate about solutions to the country’s high and rising suicide rate is contentious and has centered around lowering economic risks for farmers. In response, the Indian government established a $1.3 billion crop insurance plan aimed at reducing the suicide rate but it is unknown if that will be sufficient or effective.

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“Public dialogue has focused on a narrative in which crop failures increase farmer debt, and cause some farmers to commit suicide. Until now, there was no data to support this claim,” says Carleton.

More than half of India’s working population is employed in rain-dependent agriculture, long known to be sensitive to climate fluctuations such as unpredictable monsoon rains, scorching heat waves, and drought. A third of India’s workers already earn below the international poverty line.

The new findings indicate that protecting these workers from major economic shortfalls during these events, through policies like crop insurance or improvements in rural credit markets, may help to rein in a rising suicide rate.

Cereal crops hit hard by extreme weather

Heat drives crop loss, which can cause ripple effects throughout the Indian economy as poor harvests drive up food prices, shrink agricultural jobs, and draw on household savings. During these times, it appears that a staggering number of people, often male heads of household, turn to suicide.

Researchers tested the links between climate change, crop yields and suicide by pairing the numbers for India’s reported suicides in each of its 32 states between 1967 and 2013, using a dataset prepared by the Indian National Crime Records Bureau, along with statistics on India’s crop yields, and high-resolution climate data.

To isolate the types of climate shocks that damage crops, they focused on temperature and rainfall during June through September, a critical period for crop productivity that is based on the average arrival and departure dates of India’s summer monsoon.

The estimates of temperature-linked suicides are probably too low, because deaths in general are underreported in India and because until 2014, national law held that attempted suicide was a criminal offense, further discouraging reporting.

Source: UC Berkeley

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Segregated cities have more noise pollution

As white people move out of neighborhoods, noise pollution rises. And noise pollution is inescapable in segregated cities, where it is worse for everyone, according to the first breakdown of noise exposure along racial, ethnic, and socioeconomic lines in the United States.

A new study is the first to examine noise pollution nationally through the lens of racial disparities and the extent to which noise is exacerbated by living in segregated cities. The study doesn’t look at how noise is linked to health, but previous studies have shown that it can be associated with acute health problems including high blood pressure and loss of sleep.

“We’ve known that poor communities and communities of color are likely more exposed to toxic landfills and air pollution, but until now we really have not heard much about noise pollution,” says lead author Joan Casey, a postdoctoral scholar in the School of Public Health at the University of California, Berkeley. “The consistent disparities in noise pollution across domains in our study surprised us.”

noise levels map of US
(Credit: UC Berkeley)

Scientists used data collected by the National Park Service. Noise-monitoring devices across the continental United States recorded 1 million hours of sound over a 13-year period ending in 2013. Based on the data, UC Berkeley and Harvard University researchers estimated the noise levels in metropolitan areas across the continental US on a neighborhood-scale—areas with 600 to 1,300 residents, on average.

The levels are an estimate of the cumulative amount of noise on an average summer day in a given location. The research doesn’t differentiate between sources of noise pollution, but major sources commonly include industrial activity, traffic, and airports.

Noise was quantified by the level that is exceeded in a place 50 percent of the time. For example, a noise level of 50 decibels in a neighborhood means that 50 percent of the time noise in this neighborhood is louder than 50 decibels.

“Noise pollution is an in-your-face form of pollution.”

Noise is measured logarithmically, so a 3-decibel increase is a doubling of the sound energy.

Previous research has shown that for every 5.5-decibel increase in sound energy in a neighborhood, the proportion of residents saying they are really annoyed about noise doubles.

“Noise pollution is an in-your-face form of pollution,” Casey says. “People are definitely aware even if they are exposed to low levels of noise.”

Researchers looked at how noise levels correlated with the demographics of neighborhoods across the country, focusing on five racial and ethnic groups: Asians, blacks, Hispanics, Native Americans, and non-Hispanic whites and found a strong correlation between noise and race: Noise pollution tends to be higher as the percentage of white residents in a neighborhood declines.

On average, as the proportion of residents that were Asian, black, or Hispanic rose, noise levels both during the day and during night were higher. For Native Americans, the data showed the inverse, which could be due to the remote locations of Native American reservations.

Neighborhoods with at least 75 percent black residents had median night-time noise levels 4 decibels higher than in neighborhoods without any black residents. The difference in noise levels between predominantly white and predominantly black neighborhoods was the largest of all races and ethnicities studied.

Further, neighborhoods with high levels of poverty and low levels education had high levels of noise. One exception was in urban neighborhoods with a high median annual income, which also had high levels of noise pollution.

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White residents in segregated metropolitan areas were exposed to higher levels of noise pollution than white residents in less segregated cities. In other words, if you’re a white person living in a more segregated city, you may hear more noise than your white counterparts in a less segregated city. In the least segregated cities, all-white communities were exposed to 38 decibels of nighttime noise on average, compared to 42.5 decibels in the most segregated cities.

“…social inequality, or segregation, makes things worse for everybody.”

Racial and ethnic minorities still bore the burden of noise pollution in segregated cities. Within every level of segregation, neighborhoods with high proportions of white residents still had the lowest levels of noise.

“In more segregated cities, you see racial disparities regardless of the segregation level of the city,” Morello-Frosch says. “But what you also see is that cities that are more segregated have higher noise levels overall for everybody.”

In more segregated cities, traffic is a large source of noise. Studies of segregation and air pollution have also found that segregated cities have worse air quality overall due to local sources of emissions, such as traffic. The need to drive more in segregated cities could also be contributing to more noise pollution in these cities.

Gene could let hearing recover from loud noises

“This is yet another study that shows that communities of color bear a disproportionate burden of pollution,” Morello-Frosch says. “But I think that the innovative piece about this work is that we also show that social inequality, or segregation, makes things worse for everybody.”

The study appears in Environmental Health Perspectives. The Robert Wood Johnson Foundation and the National Cancer Institute funded the work.

Source: UC Berkeley

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Smelling our food may make us gain weight

Our sense of smell is key to the enjoyment of food, so it may be no surprise that obese mice in a recent study who lost their sense of smell also lost weight.

What’s surprising, however, is that these slimmed-down but smell-deficient mice ate the same amount of fatty food as mice that retained their sense of smell and ballooned to twice their normal weight.

Further, super smeller mice—those with a boosted sense of smell—got even fatter on a high-fat diet than did mice with normal smell.

The findings suggest that the odor of what we eat may play an important role in how the body deals with calories. If you can’t smell your food, you may burn it rather than store it.

“If we can validate this in humans, perhaps we can actually make a drug that doesn’t interfere with smell but still blocks that metabolic circuitry. That would be amazing.”

The results point to a key connection between the olfactory or smell system and regions of the brain that regulate metabolism, in particular the hypothalamus, though the neural circuits are still unknown.

“This paper is one of the first studies that really shows if we manipulate olfactory inputs we can actually alter how the brain perceives energy balance, and how the brain regulates energy balance,” says Céline Riera, a former postdoctoral fellow at the University of California, Berkeley, who is now at Cedars-Sinai Medical Center in Los Angeles.

Humans who lose their sense of smell because of age, injury, or diseases such as Parkinson’s often become anorexic, but the cause has been unclear because loss of pleasure in eating also leads to depression, which itself can cause loss of appetite.

The new study, published in Cell Metabolism, implies that the loss of smell itself plays a role, and suggests possible interventions for those who have lost their smell as well as those having trouble losing weight.

“Sensory systems play a role in metabolism. Weight gain isn’t purely a measure of the calories taken in; it’s also related to how those calories are perceived,” says senior author Andrew Dillin, chair of stem cell research and professor of molecular and cell biology. “If we can validate this in humans, perhaps we can actually make a drug that doesn’t interfere with smell but still blocks that metabolic circuitry. That would be amazing.”

Mice as well as humans are more sensitive to smells when they are hungry than after they’ve eaten, so perhaps the lack of smell tricks the body into thinking it has already eaten. While searching for food, the body stores calories in case it’s unsuccessful. Once food is secured, the body feels free to burn it.

Lean, mean burning machines

For the study, researchers used gene therapy to destroy olfactory neurons in the noses of adult mice. But they spared stem cells, so the animals lost their sense of smell only temporarily—for about three weeks—before the olfactory neurons regrew.

There’s no scientific proof that our sense of smell stinks

The smell-deficient mice rapidly burned calories by up-regulating their sympathetic nervous system, which is known to increase fat burning. The mice turned their beige fat cells—the subcutaneous fat storage cells that accumulate around our thighs and midriffs—into brown fat cells, which burn fatty acids to produce heat. Some turned almost all of their beige fat into brown fat, becoming lean, mean burning machines.

In these mice, white fat cells—the storage cells that cluster around our internal organs and are associated with poor health outcomes—also shrank in size.

The obese mice, which had also developed glucose intolerance—a condition that leads to diabetes—not only lost weight on a high-fat diet, but also regained normal glucose tolerance.

“You could wipe out their smell for maybe six months and then let the olfactory neurons grow back, after they’ve got their metabolic program rewired.”

On the negative side, the loss of smell was accompanied by a large increase in levels of the hormone noradrenaline, which is a stress response tied to the sympathetic nervous system. In humans, such a sustained rise in this hormone could lead to a heart attack.

Though it would be a drastic step to eliminate smell in humans wanting to lose weight, it might be a viable alternative for the morbidly obese contemplating stomach stapling or bariatric surgery, even with the increased noradrenaline, Dillin says.

“For that small group of people, you could wipe out their smell for maybe six months and then let the olfactory neurons grow back, after they’ve got their metabolic program rewired.”

No-smellers and super-smellers

The researchers developed two different techniques to temporarily block the sense of smell in adult mice. In one, they genetically engineered mice to express a diphtheria receptor in their olfactory neurons, which reach from the nose’s odor receptors to the olfactory center in the brain. When diphtheria toxin was sprayed into their nose, the neurons died, rendering the mice smell-deficient until the stem cells regenerated them.

Small changes may help us avoid weight gain

Separately, they also engineered a benign virus to carry the receptor into olfactory cells only via inhalation. Diphtheria toxin again knocked out their sense of smell for about three weeks.

In both cases, the smell-deficient mice ate as much of the high-fat food as did the mice that could still smell. But while the smell-deficient mice gained at most 10 percent more weight, going from 25-30 grams to 33 grams, the normal mice gained about 100 percent of their normal weight, ballooning up to 60 grams. For the former, insulin sensitivity and response to glucose—both of which are disrupted in metabolic disorders like obesity—remained normal.

Mice that were already obese lost weight after their smell was knocked out, slimming down to the size of normal mice while still eating a high-fat diet. These mice lost only fat weight, with no effect on muscle, organ, or bone mass.

The researchers then teamed up with colleagues in Germany who have a strain of mice that are super smellers, with more acute olfactory nerves, and discovered that they gained more weight on a standard diet than did normal mice.

“People with eating disorders sometimes have a hard time controlling how much food they are eating and they have a lot of cravings,” Riera says.

“We think olfactory neurons are very important for controlling pleasure of food and if we have a way to modulate this pathway, we might be able to block cravings in these people and help them with managing their food intake.”

Other researchers from UC Berkley and from the Max Planck Institute for Metabolism Research and the Salk Institute for Biological Studies. The Howard Hughes Medical Institute, the Glenn Center for Research on Aging, and the American Diabetes Association supported the work.

Source: UC Berkeley

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