Scientists have figured out how to make tiny individual films—each just a few atoms high—and stack them for use in new kinds of electronics.
Over the past half-century, scientists have shaved silicon films down to just a wisp of atoms in pursuit of smaller, faster electronics. For the next set of breakthroughs, though, they’ll need new ways to build even tinier and more powerful devices.
In a study that appears in Nature, researchers describe an innovative method to make stacks of thin, uniform layers of semiconductors just a few atoms thick which could expand capabilities for devices like solar cells and cell phones.
“When the material itself is just atoms thick, every little stray atom is a problem.”
Stacking thin layers of materials offers a range of possibilities for making electronic devices with unique properties. But manufacturing them is a delicate process, with little room for error, researchers say.
“The scale of the problem we’re looking at is, imagine trying to lay down a flat sheet of plastic wrap the size of Chicago without getting any air bubbles in it,” says Jiwoong Park, a professor of chemistry at the University of Chicago and at the Institute for Molecular Engineering and the James Franck Institute. “When the material itself is just atoms thick, every little stray atom is a problem.”
Today, these layers are “grown” instead of stacking them on top of one another. But that means the bottom layers are subjected to harsh growth conditions such as high temperatures while the new ones are added—a process that limits the materials with which to make them.
For the new process, Park’s team did something different. They made the films individually, then put them into a vacuum, peeled them off, and stuck them to one another, like Post-it notes.
This allowed scientists to make films that were connected with weak bonds instead of stronger covalent bonds—interfering less with the perfect surfaces between the layers.
“The films, vertically controlled at the atomic-level, are exceptionally high-quality over entire wafers,” says postdoctoral associate Kibum Kang, the study’s first author.
Graduate student Kan-Heng Lee, a co-first author of the study, then tested the films’ electrical properties by making them into devices and showed that their functions can be designed on the atomic scale, which could allow them to serve as the essential ingredient for future computer chips.
The method opens up a myriad of possibilities for such films. They can be made on top of water or plastics; they can be made to detach by dipping them into water; and they can be carved or patterned with an ion beam.
Researchers are exploring the full range of what can be done with the method, which they said is simple and cost-effective.
“We expect this new method to accelerate the discovery of novel materials, as well as enabling large-scale manufacturing,” Park says.
Researchers from Cornell University are coauthors of the study. The US Air Force, the National Science Foundation, and the National Research Foundation of Korea funded the work.
By studying a massive set of genetic variants of an ancient protein, scientists have been able to examine the myriad other ways that evolution could have turned out. Their work reveals the key role random chance plays in the history of evolution.
The study is the first to subject reconstructed ancestral proteins to deep mutational scanning—a state-of-the-art technique for characterizing massive libraries of protein variants. The strategy allowed them to compare the path that evolution actually took in the deep past to the millions of alternative routes that could have been taken, but were not.
Starting with a resurrected version of an ancient protein that evolved a new function some 500 million years ago—a function critical to human biology today—the researchers synthesized a massive library of genetic variants and used deep mutational scanning to analyze their functions. They found more than 800 different ways that the protein could have evolved to carry out the new function as well, or better than, the one that evolved historically.
The researchers showed that chance mutations early in the protein’s history played a key role in determining which ones could occur later. As a result, the specific outcome of evolution depended critically on the way a serial chain of chance events unfolded.
“By comparing what happened in history to all the other paths that could have produced the same result, we saw how idiosyncratic evolution is,” says Tyler Starr, a graduate student in biochemistry and molecular biology at the University of Chicago, who performed the paper’s experiments.
“People often assume that everything in biology is perfectly adapted for its function. We found that what evolved was just one possibility out of many that were just as good, or even better, functionally than what we happened to end up with today,” he explains.
Back through time
Over the last 15 years, Thornton, senior author on the new study and a professor in ecology and evolution and human genetics at the university, led research that pioneered “molecular time travel” using ancestral protein reconstruction.
In 2013, his team resurrected and analyzed the functions of the ancestors of a family of proteins called steroid hormone receptors, which mediate the effects of hormones like testosterone and estrogen on sexual reproduction, development, physiology, and cancer. The body’s various receptors recognize different hormones and, in turn, activate the expression of different target genes, which they accomplish by binding specifically to DNA sequences called response elements near those targets.
“There’s nothing special about the history that happened, except that a few chance steps brought us to this singular chance outcome.”
Thornton’s group inferred the genetic sequences of ancient receptor proteins by statistically working their way back down the tree of life from a database of hundreds of present-day receptor sequences. They synthesized genes corresponding to these ancient proteins, expressed them in the lab, and measured their functions.
They found that the ancestor of the family behaved like an estrogen receptor—recognizing only estrogens and binding to estrogen response elements—but during one specific interval of history, they evolved into a descendant group capable of recognizing other steroid hormones and binding to a new class of response elements. The researchers found that three key mutations before the emergence of vertebrate animals caused the ancestral receptor to evolve its ability to bind to the new target sequences.
That work set the stage for the current study. Knowing precisely how evolution played out in the past, Thornton’s group asked: Was this the only evolutionary path to evolving the new function? Was it the most effective one, or the easiest to achieve? Or was it simply one of many possibilities?
Paths not taken
Starr began working on the project during his first year as a graduate student, developing the technique to assess massive numbers of variants of the ancestral receptor for their ability to bind the new response element.
First, he engineered strains of yeast in which the ancestral or new response elements drive expression of a fluorescent reporter gene. He then synthesized a library of ancestral proteins containing all possible combinations of amino acids at the four key sites in the receptor that recognize DNA—160,000 in all, comprising all possible evolutionary paths that this critical part of the protein could have followed—and introduced this library into the engineered yeast.
He sorted hundreds of millions of yeast cells by their fluorescence using a laser-driven device, and then used high-throughput sequencing to associate each receptor variant with its ability to carry out the ancestral function and the new function.
Most of the variants failed to function at all, and some maintained the ancestral function. But Starr found 828 new versions of the protein that could carry out the new function as well, or better than, the one that evolved during history. Remarkably, evolution could have accessed many of these even more easily than the historical “solution,” but it happened not to, apparently wandering around the space of possible mutations until it arrived at the version of the protein in our bodies today.
“We all share the same gene sequence for this protein, so it might seem like evolutionary destiny, as if we’ve arrived at the best possible version. But there are hundreds of other directions that evolution could just as well have taken,” Thornton says. “There’s nothing special about the history that happened, except that a few chance steps brought us to this singular chance outcome.”
Thornton says that deep mutational scanning will be a powerful tool for evolutionary biologists, geneticists and biochemists, and he looks forward to using the approach on successive ancestors at different points in history to see how the set of possible outcomes changed through time.
“We have a molecular time machine to go back to the past, and once we’re there, we can simultaneously follow every alternate history that could possibly have played out,” Thornton says. “It’s a molecular version of every evolutionary biologist’s dream.”
People in northern China have a reduced life expectancy when compared with people living in the south due to higher concentrations of air pollution, a new study suggests.
The study also outlines a new method researchers developed to calculate the impact of air pollution on life expectancy.
There are currently an estimated 4.5 billion people around the world exposed to levels of particulate air pollution that are at least twice what the World Health Organization considers safe. Yet the impact of sustained exposure to pollution on a person’s life expectancy has largely remained a vexingly unanswered question.
“…the impact on life expectancy in many parts of the world [is] similar to the effects of every man, woman, and child smoking cigarettes for several decades…”
The study finds that a Chinese policy is unintentionally causing people in northern China to live 3.1 years less than people in the south. The study found that this was due to air pollution concentrations that are 46 percent higher in the north than in the south.
The new findings imply that every additional 10 micrograms per cubic meter of particulate matter pollution reduces life expectancy by 0.6 years. The elevated mortality is entirely due to an increase in cardiorespiratory deaths, indicating that air pollution is the cause of reduced life expectancies to the north.
“These results greatly strengthen the case that long-term exposure to particulates air pollution causes substantial reductions in life expectancy. They indicate that particulates are the greatest current environmental risk to human health, with the impact on life expectancy in many parts of the world similar to the effects of every man, woman, and child smoking cigarettes for several decades,” says study coauthor Michael Greenstone, director of the Energy Policy Institute at the University of Chicago and a professor in economics.
“The histories of the United States, parts of Europe, Japan, and a handful of other countries teach us that air pollution can be reduced, but it requires robust policy and enforcement,” Greenstone says.
The study exploits China’s Huai River policy, which provided free coal to power boilers for winter heating to people living north of the river and provided almost no resources toward heating south of the river. The policy’s partial provision of heating occurred because China did not have enough resources to provide free coal nationwide.
“Unveiling this important information helps build the case for policies that ultimately serve to improve the lives of the Chinese people…”
Additionally, since migration was greatly restricted, people exposed to pollution were generally not able to migrate to less polluted areas. Together, the discrete change in policy at the river’s edge and the migration restrictions provide the basis for a powerful natural experiment that offers an opportunity to isolate the impact of sustained exposure to particulates air pollution from other factors that affect health.
“Unveiling this important information helps build the case for policies that ultimately serve to improve the lives of the Chinese people and the lives of those globally who suffer from high levels of air pollution,” says study coauthor Maigeng Zhou, deputy director of the National Center for Chronic and Noncommunicable Disease Control and Prevention in the Chinese Center for Disease Control and Prevention.
Overall, the study provides solutions to several challenges that have plagued previous research. In particular, prior studies rely on research designs that may be unlikely to isolate the causal effects of air pollution; measure the effect of pollution exposure for relatively short periods of time (e.g., weekly or annually), failing to shed light on the effect of sustained exposure; examine settings with much lower pollution concentrations than those currently faced by billions of people in countries, including China and India, leaving questions about their applicability unanswered; measure effects on mortality rates but leave the full loss of life expectancy unanswered.
“The study’s unique design provides solutions to several challenges that have been difficult to solve,” says coauthor Maoyong Fan, an associate professor at Ball State University. “The Huai River policy also provides a research design that can be used to explore a variety of other questions about the long-run consequences of exposure to high levels of pollution.”
The study follows on an earlier study, conducted by some of the same researchers, which also utilized the unique Huai River design. Despite using data from two separate time periods, both studies revealed the same basic relationship between pollution and life expectancy.
The new study’s more recent data, however, cover a population eight times greater than the previous one. It also provides direct evidence on smaller pollution particles that are more often the subject of environmental regulations.
“This new study provides an important opportunity to assess the validity of our previous findings. The striking finding is that both studies produced remarkably similar results, increasing our confidence that we have uncovered the causal relationship between particulates air pollution and life expectancy,” says Avraham Ebenstein, a lecturer in the environmental economics and management department at Hebrew University of Jerusalem and an author of both studies.
Since the earlier paper, China has increased its efforts to confront its air pollution challenge. China is switching its primary source of heating from coal-fired boilers to gas-fired or electric units, and it has shut down many polluting plants. The consequence is that particulate air pollution in some of China’s most polluted cities, such as Beijing, has improved significantly.
“Our findings show that these changes will bring about significant health benefits for the Chinese people in the long run,” says coauthor Guojun He, an assistant professor at the Hong Kong University of Science and Technology. “If all of China were brought into compliance with its Class I standards for PM10 (40), more than 3.7 billion life-years will be saved.”
The Air Quality-Life Index
Importantly, the results from this paper can be generalized to quantify the number of years that air pollution reduces lifespans around the globe—not just in China. Specifically, Greenstone and his colleagues at EPIC used the finding that an additional 10 micrograms per cubic meter of PM10 reduces life expectancy by 0.6 years to develop a new pollution index, the Air Quality-Life Index.
The index allows users to better understand the impact of air pollution on their lives by calculating how much longer they would live if the pollution in the air they breathe were brought into compliance with national or WHO standards. It also serves as an important complement to the frequently used Air Quality Index, which is a complicated function of air pollution concentrations and does not map directly to long-term human health.
“The AQLI uses the critical data and information gathered from our China research and applies it to every country, allowing the billions of people around the world who are exposed to high air pollution levels to estimate how much longer they would live if they breathed cleaner air,” said Greenstone.
A new study challenges the idea that medical students’ empathy declines during their time at medical school.
Previous studies that reported an erosion of empathy during medical training relied on one self-reported assessment of cognitive empathy.
Some studies have documented troubling declines in empathy during medical training—the steepest of which are believed to occur between the second and third years of medical school, when students begin clinical training and empathetic communication is critical, but this new study may refute those findings.
The relationship between a doctor and patient relies heavily on the physician’s capacity to empathize with or be sensitive to a patient’s emotional state. Empathy has been associated with patients’ increased adherence to treatment, fewer malpractice complaints, improved patient satisfaction, and favorable health outcomes.
The authors of the new study point to the interaction of two facets of empathy: cognitive and affective.
“Cognitive empathy is the ability to recognize and understand another person’s experience, to communicate and confirm that understanding, and to act in an appropriate and helpful manner without necessarily sharing his or her emotions,” says Jean Decety, a professor of psychology and psychiatry, and lead author of the new study. “Affective, or emotional, empathy is being attuned to someone else’s emotions, feeling what he or she feels.”
Previous studies that reported an erosion of empathy during medical training relied on one self-reported assessment of cognitive empathy. Often emphasized as most important in a clinical setting, it enables physicians to understand how their patients feel without having an emotional attunement. Affective empathy has long been thought to impede a physician’s effectiveness in diagnosing and treating patients.
Decety and colleagues contend that both components are important in patient-physician interactions, as doctors must be able to both accurately perceive and respond to their patients’ emotional states.
In this study, a variety of subjective and objective measures helped provide a more complete understanding of the mechanisms that contribute to changes in empathetic capacity over the course of medical school. It also shed light on current discrepancies and inconsistencies within medical empathy literature.
Researchers designed a study that followed 129 medical students from Loyola University, Northwestern University, and the University of Chicago during their first three years of medical school. At the beginning and end of each year, students completed a series of online surveys and behavioral tasks designed to objectively assess different components of empathy.
The first survey was the Jefferson Scale of Physician Empathy, one of the most common self-assessment questionnaires in the field and thought to primarily evaluate the cognitive aspects of empathy.
“We sought to replicate the results of previous studies that used this self-report measure,” says Decety. “We did, in fact, see declines in assessment scores over the course of student training, which is in line with other studies that used this method.”
The research team was interested in more than just a self-report on cognitive empathy, however. They wanted to tease out how the individual components of empathy changed over time, so they also administered the Questionnaire of Cognitive and Affective Empathy. This assessment is designed to reliably distinguish between the two facets of empathy, based on the social cognitive neuroscience literature on empathy and its underlying brain mechanisms.
At each appointment, students also were asked to complete a set of computerized tasks aimed at objectively evaluating their ability to recognize different mental and emotional states and sensitivity to the pain of others.
In contrast to the results of the Jefferson Scale questionnaire, student scores on the Questionnaire of Cognitive and Affective Empathy improved over time. Specifically, they found that both affective empathy and cognitive empathy increased during medical training. Similarly, medical students showed both greater sensitivity to facial expressions of pain and progress in their ability to quickly and accurately recognize others’ emotional states.
The study challenges the view of an overall decline of empathy during medical training. The authors write: “We found that changes in empathy during medical training are not necessarily negative—the narrative appears to be much more complicated than we initially thought and illustrates how problematic it is to rely on a single, subjective measure to evaluate a complex psychological construct.”
The facets of empathy that improved, including perspective-taking and understanding others’ emotions, are thought to be most important to physician empathy—and the most susceptible to change through teaching. Given the importance of empathy in the clinical setting, characterizing and understanding changes in student empathy has important implications for future teaching interventions, the authors contend.
Observed changes also may be the result of a curriculum that focuses on understanding the patient’s perspective and conveying that to the patient. Many medical schools, including those included in this work, have explicit empathy curricula aimed at developing these skills, and the findings in this study could indicate these programs create positive changes.
A team of scientists has designed a way to use microscopic capsules made out of DNA to deliver a payload of tiny molecules directly into a cell.
The technique gives scientists an opportunity to understand certain interactions among cells that have previously been hard to track.
“It’s really a molecular platform,” says Yamuna Krishnan, a professor in chemistry at the University of Chicago and coauthor of the study. “There are a host of research problems from cardiology to neurobiology that need a system like this to study very fast molecular phenomena, so it could be applied in a variety of ways.”
Cells talk to each other in chemical whispers that occur too fast for scientists to accurately study, Krishnan says. Her team aimed at one class of such chemical communications, known as neurosteroids.
Scientists know neurosteroids are involved in neuronal health, but they’re difficult to study because they operate on hair triggers.
“The moment you add a neurosteroid, the neuron’s already fired,” Krishnan says.
Researchers want a blow-by-blow account of what happens in the cell as the neurosteroid plays its part in the intricate signaling dance inside a neuron. To do so, they needed to get the neurosteroids to the cell inside a little package, release them on cue and then track what happens. But it’s difficult to make a delivery system so airtight that it doesn’t leak a couple of molecules before everything’s set up.
For this task, Krishnan had a solution: Her lab builds tiny machines out of DNA. It’s a good material because like a set of Legos, it has standard interlocking pieces that make it easy to build into configurations. And since it’s made out of parts already in the body, it can dissolve harmlessly once its purpose is achieved.
The lab made tiny structures—icosahedral, like a 20-sided die—with two halves that clamp together around a payload of molecules to form a capsule. Each capsule is just 20 nanometers across; that’s a thousand times smaller than the width of a human hair.
The next step was to send them to key locations inside the body by finding the right molecular “addresses” to particular cells, and gluing them onto the capsule. (Scientists find these addresses by studying how viruses and bacteria hone in on particular parts of the body.) To release the payload from the capsule, the scientists simply shine a light on the cells.
They tested and confirmed the system in worms and were able to measure the kinetics of the neurosteroids, previously an elusive process, the authors say.
Someday, Krishnan says, the technology could be used to deliver drugs or treatment to certain parts of the body, but theirs was a case study to explore the method as a way to better understand our own bodies and how they work.
The Human Frontier Science Program, National Institutes of Health, National Science Foundation through the Materials Research Science & Engineering Center program, and University of Chicago startup funds provided funding for the research.
A team of scientists appear to have detected the first X-rays coming from a type Ia supernova.
Astronomers are fond of type Ia supernovas, created when a white dwarf star in a two-star system undergoes a thermonuclear explosion, because they burn at a specific brightness. This allows scientists to calculate how far away they are from Earth, and thus to map distances in the universe.
“It is surprising what you can learn from so few photons…”
A few years ago, however, scientists began to find type Ia supernovas with a strange optical signature that suggested they carried a very dense cloak of circumstellar material surrounding them.
Such dense material is normally only seen from a different type of supernova called type II, and is created when massive stars start to lose mass. The ejected mass collects around the star; then, when the star collapses, the explosion sends a shockwave hurtling at supersonic speeds into this dense material, producing a shower of X-rays. Thus, we regularly see X-rays from type II supernovas, but they have never been seen from type Ia supernovas.
When the team studied the supernova 2012ca, recorded by the Chandra X-ray Observatory, however, they detected X-ray photons coming from the scene.
“Although other type Ia’s with circumstellar material were thought to have similarly high densities based on their optical spectra, we have never before detected them with X-rays,” says study coauthor Vikram Dwarkadas, research associate professor in the astronomy and astrophysics department at the University of Chicago.
The amounts of X-rays they found were small—they counted 33 photons in the first observation a year and a half after the supernova exploded, and ten in another about 200 days later—but present.
“This certainly appears to be a Ia supernova with substantial circumstellar material, and it looks as though it’s very dense,” he says. “What we saw suggests a density about a million times higher what we thought was the maximum around Ia’s.”
It’s thought that white dwarfs don’t lose mass before they explode. The usual explanation for the circumstellar material is that it would have come from a companion star in the system, but the amount of mass suggested by this measurement was very large, Dwarkadas says—far larger than one could expect from most companion stars.
“Even the most massive stars do not have such high mass-loss rates on a regular basis,” he says. “This once again raises the question of how exactly these strange supernovas form.”
“If it’s truly a Ia, that’s a very interesting development because we have no idea why it would have so much circumstellar material around it,” he says.
“It is surprising what you can learn from so few photons,” says Chris Bochenek, lead author of the study and a graduate student at the California Institute for Technology, whose work on the study formed his undergraduate thesis at the University of Chicago. “With only tens of them, we were able to infer that the dense gas around the supernova is likely clumpy or in a disk.”
The C. elegans roundworm sees by eating, sucking in big gulps of bacteria to learn about its surrounding environment.
For a new study, scientists used a mathematical model to explain these eating bursts. What they discovered clarifies animals’ feeding behavior and the science of decision-making.
“It’s an interesting model for understanding the processes that underlie how animals decide where and when to eat,” says lead author Monika Scholz, an international student research fellow with the University of Chicago’s biophysical sciences program who is now at Princeton University. “For these worms, it’s all about the balance between speed and accuracy.”
Roundworms live in big colonies in soil, such as compost piles, searching for bacteria to eat. Because they lack eyes, roundworms taste as they travel, but every gulp comes with a cost: The bite could contain delicious bacteria, or toxins, or nothing, in which case they’ve spent energy with no outcome.
The straightforward prediction would say the worms should eat a lot when food it’s available, and stop when there is no food. But the ability to collect data on worm feeding over longer periods—an hour or more rather than just a minute or two—allowed researchers to notice an odd burst feeding pattern that didn’t always correlate to the amount of food available. In particular, the worms’ feeding intensified when the amount of food quickly fluctuated.
When the data are laid out with a mathematical model that analyzes decisions, the pattern makes more sense, Scholz says.
“What we see is it’s an evidence accumulation task. Whenever the worm needs more information, it keeps taking bites. But if I keep changing the conditions while you’re still deciding, the information is worthless.
“Most organisms live on the boundary of just enough to survive, so there is high evolutionary pressure to be good at these decisions.”
“So the worm keeps trying to accumulate more and more evidence to make its decision, and you see this erratic pattern.”
Understanding these systems is helpful because all animals, including humans, make similar decisions about when and where to eat.
“Most organisms live on the boundary of just enough to survive, so there is high evolutionary pressure to be good at these decisions. Systems for regulating food intake have evolved under situations where food is scarce,” Scholz says.
“Currently much of our understanding of decision-making is investigated at two levels: At a purely theoretical level that is typically very removed from actual data, and psychology/animal behavior studies in complex mammals, which are complicated due to a lot of other factors that influence decision-making.
“So what you have is two very distant levels of understanding. What research like this can do—basic research in simple organisms—is bridge that gap.”
New research suggests that people think about the question, “If you could save the lives of five people by pushing another bystander in front of a train to his death, would you do it?” differently if they hear it asked in a language other than their native one.
Psychologists found in past research that people facing such a dilemma while communicating in a foreign language are far more willing to sacrifice the bystander than those using their native tongue. In a new paper, the researchers take a major step toward understanding why that happens.
“Until now, we and others have described how using a foreign language affects the way that we think,” says Boaz Keysar, a psychology professor at the University of Chicago in whose lab the research was conducted. “We always had explanations, but they were not tested directly. This is really the first paper that explains why, with evidence.”
Less averse to breaking taboos?
Through a series of experiments, Keysar and his colleagues explore whether the decision people make in the train dilemma is due to a reduction in the emotional aversion to breaking an ingrained taboo, an increase in deliberation thought to be associated with a utilitarian sense of maximizing the greater good or some combination of the two.
“My prediction was that we’d find that the difference is in how much they care about the common good. But it’s not that at all.”
“We discovered that people using a foreign language were not any more concerned with maximizing the greater good,” says lead author Sayuri Hayakawa, a doctoral student in psychology. “But rather, were less averse to violating the taboos that can interfere with making utility-maximizing choices.”
The researchers, including Albert Costa and Joanna Corey from Pompeu Fabra University in Barcelona, propose that using a foreign language gives people some emotional distance and that allowed them to take the more utilitarian action.
“I thought it was very surprising,” Keysar says. “My prediction was that we’d find that the difference is in how much they care about the common good. But it’s not that at all.”
Studies from around the world suggest that using a foreign language makes people more utilitarian. Speaking a foreign language slows you down and requires that you concentrate to understand. Scientists have hypothesized that the result is a more deliberative frame of mind that makes the utilitarian benefit of saving five lives outweigh the aversion to pushing a man to his death.
But Keysar’s own experience speaking a foreign language—English—gave him the sense that emotion was important. English just didn’t have the visceral resonance for him as his native Hebrew. It wasn’t as intimately connected to emotion, a feeling shared by many bilingual people and corroborated by numerous lab studies.
“Your native language is acquired from your family, from your friends, from television,” Hayakawa says. “It becomes infused with all these emotions.”
Foreign languages are often learned later in life in classrooms, and may not activate feelings, including aversive feelings, as strongly.
The problem is that either the “more utilitarian” or the “less emotional” process would produce the same behavior.
To help figure out which was actually responsible, the psychologists worked with David Tannenbaum, a postdoctoral research fellow at the University of Chicago Booth School of Business, at the time of the study. Tannenbaum is an expert at a technique called process dissociation, which allows researchers to tease out and measure the relative importance of different factors in a decision process.
For the paper, the researchers did six separate studies with six different groups, including native speakers of English, German, and Spanish. Each also spoke one of the other languages, so that all possible combinations were equally represented. Each person was randomly assigned to use either his or her native language or second language throughout the experiment.
“…people using a foreign language were not paying any more attention to the lives saved, but definitely were less averse to breaking these kinds of rules.”
Participants read an array of paired scenarios that varied systematically in key ways. For example, instead of killing a man to save five people from death, they might be asked if they would kill him to save five people from minor injuries. The taboo act of killing the man is the same, but the consequences vary.
“If you have enough of these paired scenarios, you can start gauging what are the factors that people are paying attention to,” Hayakawa says.
“We found that people using a foreign language were not paying any more attention to the lives saved, but definitely were less averse to breaking these kinds of rules. So if you ask the classic question, ‘Is it the head or the heart?’ It seems that the foreign language gets to the heart.”
The researchers are next looking at why that is. Does using a foreign language blunt people’s mental visualization of the consequences of their actions, contributing to their increased willingness to make the sacrifice? And do they create less mental imagery because of differences in how foreign language use affects which memories come to mind?
The researchers are also starting to investigate whether their lab results apply in real-world situations where the stakes are high. A study Keysar’s team is initiating in Israel looks at whether the parties in a peace negotiation assess the same proposal differently if they see it in their own language or the language of their negotiating partner.
Keysar is also interested in looking at whether language can be usefully considered in decisions made by doctors speaking a foreign language.
“You might be able to predict differences in medical decision-making depending on the language that you use,” he says. “In some cases you might prefer a stronger emotional engagement, in some you might not.”
The John Templeton Foundation, the National Science Foundation, the Spanish Government, the Ministry of Economy and Competitiveness, the Catalan Government, the European Research Council, and the University of Chicago provided funding for the research.
Using health insurance claims data from more than 480,000 people in nearly 130,000 families, researchers have created a new classification of common diseases based on how often they occur among genetically-related individuals.
Researchers hope the work, published this week in Nature Genetics, will help physicians make better diagnoses and treat root causes instead of symptoms.
“Understanding genetic similarities between diseases may mean that drugs that are effective for one disease may be effective for another one,” says senior author Andrey Rzhetsky, professor of medicine and human genetics at the University of Chicago. “And for those diseases with a large environmental component, that means we can perhaps prevent them by changing the environment.”
The results of the study suggest that standard disease classifications–called nosologies–based on symptoms or anatomy may miss connections between diseases with the same underlying causes. For example, the new study showed that migraine, typically classified as a disease of the central nervous system, appeared to be most genetically similar to irritable bowel syndrome, an inflammatory disorder of the intestine.
Rzhetsky and a team of researchers analyzed records from Truven MarketScan, a database of de-identified patient data from more than 40 million families in the United States. They selected a subset of records based on how long parents and their children were covered under the same insurance plan within a time frame most likely to capture when children were living in the same home with their parents. They used this massive data set to estimate genetic and environmental correlations between diseases.
Next, using statistical methods developed to create evolutionary trees of organisms, the team created a disease classification based on two measures. One focused on shared genetic correlations of diseases, or how often diseases occurred among genetically-related individuals, such as parents and children. The other focused on the familial environment, or how often diseases occurred among those sharing a home but who had no or partially matching genetic backgrounds, such as spouses and siblings.
The results focused on 29 diseases that were well represented in both children and parents to build new classification trees. Each “branch” of the tree is built with pairs of diseases that are highly correlated with each other, meaning they occur frequently together, either between parents and children sharing the same genes, or family members sharing the same living environment.
“The large number of families in this study allowed us to obtain precise estimates of genetic and environmental correlations, representing the common causes of multiple different diseases,” says Kanix Wang, a graduate student and lead author of the study. “Using these shared genetic and environmental causes, we created a new system to classify diseases based on their intrinsic biology.”
Genetic similarities between diseases tended to be stronger than their corresponding environmental correlations. For the majority of neuropsychiatric diseases, such as schizophrenia, bipolar disorder, and substance abuse, however, environmental correlations are nearly as strong as genetic ones. This suggests there are elements of the shared, family environment that could be changed to help prevent these disorders.
The researchers also compared their results to the widely used International Classification of Diseases Version 9 (ICD-9) and found additional, unexpected groupings of diseases. For example, type 1 diabetes, an autoimmune endocrine disease, has a high genetic correlation with hypertension, a disease of the circulatory system. The researchers also saw high genetic correlations across common, apparently dissimilar diseases such as asthma, allergic rhinitis, osteoarthritis, and dermatitis.
The study received support from the Defense Advanced Research Projects Agency (DARPA) Big Mechanism program, the National Institutes of Health, and a gift from Liz and Kent Dauten. Additional authors are from the University of Chicago, Microsoft Research, and Vanderbilt University.
The forerunners of mammals in the Jurassic Period evolved to glide and live in trees using long limbs, long hand and foot fingers, and wing-like membranes, two 160 million-year-old fossils discovered in China suggest.
The discovery indicates that the volant, or flying, way of life evolved among mammalian ancestors 100 million years earlier than the first modern mammal fliers.
“These Jurassic mammals are truly ‘the first in glide,’” says Zhe-Xi Luo, professor of organismal biology and anatomy at the University of Chicago and coauthor of two papers in Nature describing the findings (paper 1, paper 2). “In a way, they got the first wings among all mammals.
“With every new mammal fossil from the Age of Dinosaurs, we continue to be surprised by how diverse mammalian forerunners were in both feeding and locomotor adaptations. The groundwork for mammals’ successful diversification today appears to have been laid long ago,” he says.
The ability to glide in the air is one of the many remarkable adaptations in mammals. Most mammals live on land, but volant mammals, including flying squirrels and bats that flap bird-like wings, made an important transition between land and aerial habitats.
The ability to glide between trees allowed the ancient animals to find food that was inaccessible to other land animals. That evolutionary advantage can still be seen among today’s mammals such as flying squirrels in North America and Asia, scaly-tailed gliders of Africa, marsupial sugar gliders of Australia, and colugos of Southeast Asia.
The Jurassic species, Maiopatagium furculiferum and Vilevolodon diplomylos, are stem mammaliaforms, long-extinct relatives of living mammals. They are haramiyidans, an entirely extinct branch on the mammalian evolutionary tree, but are considered to be among forerunners to modern mammals.
Both samples show the exquisitely fossilized, wing-like skin membranes between their front and back limbs. They also show many skeletal features in their shoulder joints and forelimbs that gave the ancient animals the agility to be capable gliders.
Evolutionarily, the two fossils—discovered in the Tiaojishan Formation northeast of Beijing, China—represent the earliest examples of gliding behavior among extinct mammal ancestors.
The newly discovered creatures also share similar ecology with modern gliders, but with some significant differences. Today, the hallmark of most mammal gliders is their herbivorous diet that typically consists of seeds, fruits, and other soft parts of flowering plants.
But Maiopatagium and Vilevolodon lived in a Jurassic world in which plant life was dominated by ferns and gymnosperm plants like cycads, gingkoes, and conifers—long before flowering plants came to dominate in the Cretaceous Period. Their way of life also was associated with feeding on these entirely different plants. This distinct diet and lifestyle evolved again some 100 million years later among modern mammals, in examples of convergent evolution and ecology.
“It’s amazing that the aerial adaptions occurred so early in the history of mammals,” says study coauthor David Grossnickle, a graduate student at the university. “Not only did these fossils show exquisite fossilization of gliding membranes, their limb, hand, and foot proportion also suggests a new gliding locomotion and behavior.”
Early mammals were once thought to have differences in anatomy from each other, with limited opportunities to inhabit different environments. The new glider fossils from the dinosaur-dominated Jurassic Period, along with numerous other fossils, however, provide strong evidence that ancestral mammals adapted to their wide-ranging environments despite competition from dinosaurs.
“Mammals are more diverse in lifestyles than other modern land vertebrates, but we wanted to find out whether early forerunners to mammals had diversified in the same way,” Luo says.
“These new fossil gliders are the first winged mammals, and they demonstrate that early mammals did indeed have a wide range of ecological diversity, which means dinosaurs likely did not dominate the Mesozoic landscape as much as previously thought.”