Chapter 15. Emotions, Aggression, and Stress
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Helen Thomson Genetic changes stemming from the trauma suffered by Holocaust survivors are capable of being passed on to their children, the clearest sign yet that one person’s life experience can affect subsequent generations. The conclusion from a research team at New York’s Mount Sinai hospital led by Rachel Yehuda stems from the genetic study of 32 Jewish men and women who had either been interned in a Nazi concentration camp, witnessed or experienced torture or who had had to hide during the second world war. They also analysed the genes of their children, who are known to have increased likelihood of stress disorders, and compared the results with Jewish families who were living outside of Europe during the war. “The gene changes in the children could only be attributed to Holocaust exposure in the parents,” said Yehuda. Her team’s work is the clearest example in humans of the transmission of trauma to a child via what is called “epigenetic inheritance” - the idea that environmental influences such as smoking, diet and stress can affect the genes of your children and possibly even grandchildren. The idea is controversial, as scientific convention states that genes contained in DNA are the only way to transmit biological information between generations. However, our genes are modified by the environment all the time, through chemical tags that attach themselves to our DNA, switching genes on and off. Recent studies suggest that some of these tags might somehow be passed through generations, meaning our environment could have and impact on our children’s health. © 2015 Guardian News and Media Limited
By Christian Jarrett If we’re being honest, most of us have at least some selfish aims – to make money, to win a promotion at work, and so on. But importantly, we pursue these goals while at the same time conforming to basic rules of decency. For example, if somebody helps us out, we’ll reciprocate, even if doing so costs us time or cash. Yet there is a minority of people out there who don’t play by these rules. These selfish individuals consider other people as mere tools to be leveraged in the pursuit of their aims. They think nothing of betrayal or backstabbing, and they basically believe everyone else is in it for themselves too. Psychologists call these people “Machiavellians,” and there’s a questionnaire that tests for this trait (one of the so-called “dark triad” of personality traits along with narcissism and psychopathy). People high in Machiavellianism are more likely to agree with statements like: It is wise to flatter important people and The best way to handle people is to tell them what they want to hear. Calling them Machiavellian is too kind. These people are basically jerks. Related Stories Inside the Brains of Happily Married Couples Lonely People’s Brains Work Differently Now a team of Hungarian researchers from the University of Pécs has scanned the brains of high scorers on Machiavellianism while they played a simple game of trust. Reporting their results in the journal Brain and Cognition, the researchers said they found that Machiavellians’ brains went into overdrive when they encountered a partner who exhibited signs of being fair and cooperative. Why? Tamas Bereczkei and his team say it’s because the Machiavellians are immediately figuring out how to exploit the situation for their own gain. The game involved four stages and the student participants — a mix of high and low scorers on Machiavellianism — played several times with different partners. First, the participants were given roughly $5 worth of Hungarian currency and had to decide how much to “invest” in their partner. Any money they invested was always tripled as it passed to their partner. © 2015, New York Media LLC.
Link ID: 21324 - Posted: 08.22.2015
By Gretchen Reynolds Sticking to a diet requires self-control and a willingness to forgo present pleasures for future benefits. Not surprisingly, almost everyone yields to temptation at least sometimes, opting for the cookie instead of the apple. Wondering why we so often override our resolve, scientists at the Laboratory for Social and Neural Systems Research at the University of Zurich recently considered the role of stress, which is linked to a variety of health problems, including weight gain. (There’s something to the rom-com cliché of the jilted lover eating ice cream directly from the carton.) But just how stress might drive us to sweets has not been altogether clear. It turns out that even mild stress may immediately alter the workings of our brains in ways that undermine willpower. For their study, published this month in Neuron, researchers recruited 51 young men who said they were trying to maintain a healthy diet and lifestyle. The men were divided into two groups, one of which served as a control, and then all were asked to skim through images of different kinds of food on a computer screen, rating them for taste and healthfulness. Next, the men in the experimental group were told to plunge a hand into a bowl of icy water for as long as they could, a test known to induce mild physiological and psychological stress. Relative to the control group, the men developed higher levels of cortisol, a stress hormone. After that, men from each group sat in a brain-scanning machine and watched pictures of paired foods flash across a screen. Generally, one of the two foods was more healthful than the other. The subjects were asked to click rapidly on which food they would choose to eat, knowing that at the end of the test they would actually be expected to eat one of these picks (chosen at random from all of their choices). © 2015 The New York Times Company
—By Chris Mooney It is still considered highly uncool to ascribe a person's political beliefs, even in part, to that person's biology: hormones, physiological responses, even brain structures and genes. And no wonder: Doing so raises all kinds of thorny, non-PC issues involving free will, determinism, toleration, and much else. There's just one problem: Published scientific research keeps going there, with ever increasing audacity (not to mention growing stacks of data). The past two weeks have seen not one but two studies published in scientific journals on the biological underpinnings of political ideology. And these studies go straight at the role of genes and the brain in shaping our views, and even our votes. First, in the American Journal of Political Science, a team of researchers including Peter Hatemi of Penn State University and Rose McDermott of Brown University studied the relationship between our deep-seated tendencies to experience fear—tendencies that vary from person to person, partly for reasons that seem rooted in our genes—and our political beliefs. What they found is that people who have more fearful disposition also tend to be more politically conservative, and less tolerant of immigrants and people of races different from their own. As McDermott carefully emphasizes, that does not mean that every conservative has a high fear disposition. "It's not that conservative people are more fearful, it's that fearful people are more conservative," as she puts it. I interviewed the paper's lead author, Peter Hatemi, about his research for my 2012 book The Republican Brain. Hatemi is both a political scientist and also a microbiologist, and as he stressed to me, "nothing is all genes, or all environment." These forces combine to make us who we are, in incredibly intricate ways. ©2015 Mother Jones
By Zoe Kleinman Technology reporter, BBC News More than 200 academics have signed an open letter criticising controversial new research suggesting a link between violent video games and aggression. The findings were released by the American Psychological Association. It set up a taskforce that reviewed hundreds of studies and papers published between 2005 and 2013. The American Psychological Association concluded while there was "no single risk factor" to blame for aggression, violent video games did contribute. "The research demonstrates a consistent relation between violent video game use and increases in aggressive behaviour, aggressive cognitions and aggressive affect, and decreases in pro-social behaviour, empathy and sensitivity to aggression," said the report. "It is the accumulation of risk factors that tends to lead to aggressive or violent behaviour. The research reviewed here demonstrates that violent video game use is one such risk factor." However, a large group of academics said they felt the methodology of the research was deeply flawed as a significant part of material included in the study had not been subjected to peer review. "I fully acknowledge that exposure to repeated violence may have short-term effects - you would be a fool to deny that - but the long-term consequences of crime and actual violent behaviour, there is just no evidence linking violent video games with that," Dr Mark Coulson, associate professor of psychology at Middlesex University and one of the signatories of the letter told the BBC. "If you play three hours of Call of Duty you might feel a little bit pumped, but you are not going to go out and mug someone." © 2015 BBC
Link ID: 21310 - Posted: 08.19.2015
John von Radowitz , Press Association Psychologists have confirmed that playing violent video games is linked to aggressive and callous behaviour. A review of almost a decade of studies found that exposure to violent video games was a "risk factor" for increased aggression. But the same team of experts said there was insufficient evidence to conclude that the influence of games such as Call Of Duty and Grand Theft Auto led to criminal acts. The findings have prompted a call for more parental control over violent scenes in video games from the American Psychological Association (APA). The original version of Doom, released in 1993, was widely controversial for its unprecedented levels of graphic violence A report from the APA task force on violent media concludes: "The research demonstrates a consistent relation between violent video game use and increases in aggressive behaviour, aggressive cognitions and aggressive affect, and decreases in pro-social behaviour, empathy and sensitivity to aggression." The report said no single influence led a person to act aggressively or violently. Rather, it was an "accumulation of risk factors" that resulted in such behaviour. It added: "The research reviewed here demonstrates that violent video game use is one such risk factor." The APA has urged game creators to increase levels of parental control over the amount of violence video games contain.
Link ID: 21301 - Posted: 08.17.2015
By PAUL GLIMCHER and MICHAEL A. LIVERMORE THE United States government recently announced an $18.7 billion settlement of claims against the oil giant BP in connection with the Deepwater Horizon oil rig explosion in April 2010, which dumped millions of barrels of oil into the Gulf of Mexico. Though some of the settlement funds are to compensate the region for economic harm, most will go to environmental restoration in affected states. Is BP getting off easy, or being unfairly penalized? This is not easy to answer. Assigning a monetary value to environmental harm is notoriously tricky. There is, after all, no market for intact ecosystems or endangered species. We don’t reveal how much we value these things in a consumer context, as goods or services for which we will or won’t pay a certain amount. Instead, we value them for their mere existence. And it is not obvious how to put a price tag on that. In an attempt to do so, economists and policy makers often rely on a technique called “contingent valuation,” which amounts to asking individuals survey questions about their willingness to pay to protect natural resources. The values generated by contingent valuation studies are frequently used to inform public policy and litigation. (If the government had gone to trial with BP, it most likely would have relied on such studies to argue for a large judgment against the company.) Contingent valuation has always aroused skepticism. Oil companies, unsurprisingly, have criticized the technique. But many economists have also been skeptical, worrying that hypothetical questions posed to ordinary citizens may not really capture their genuine sense of environmental value. Even the Obama administration seems to discount contingent valuation, choosing to exclude data from this technique in 2014 when issuing a new rule to reduce the number of fish killed by power plants. © 2015 The New York Times Company
Susanne Ahmari Some 40 million people worldwide have been diagnosed with anxiety disorders. In Anxious, Joseph LeDoux presents a rigorous, in-depth guide to the history, philosophy and scientific exploration of this widespread emotional state. An eminent neuroscientist and author of The Emotional Brain (Simon & Schuster, 1996) and The Synaptic Self (Viking, 2002), he offers a magisterial review of the role of mind and brain in the generation of both unconscious defensive responses and consciously expressed anxiety. LeDoux looks first at how our understanding of anxiety has evolved. He starts with ancient etymology (the Greek angh signified constriction) and moves on to Sigmund Freud's view of anxiety as the “root of most if not all mental maladies”, and philosopher Søren Kierkegaard's perspective on it as existential, evolving from the dread that stems from freedom of choice. He then lays out the core distinction between fear and anxiety. Fear he defines as anticipation of danger from a physically present threat (a grizzly bear in front of you); anxiety, as anticipation of an uncertain threat (potential predators roaming outside your tent). But although 'fear' and 'anxiety' are excellent descriptors of conscious feelings, LeDoux shows, they should not be used to describe the unconscious mental processes and neural circuits associated with these emotions. Instead of thinking of those processes as “fear stimuli activate a fear system to produce fear responses”, he proposes conceptualizing them as “threat stimuli elicit defense responses via activation of a defensive system”. This is a subtle distinction, and LeDoux makes an excellent case that it is an important foundation for rigorous research into the neural underpinnings of the conscious and unconscious processes that subserve anxiety. © 2015 Macmillan Publishers Limited.
Link ID: 21274 - Posted: 08.08.2015
By Kristin Leutwyler Ozelli Researchers are just now beginning to discover how different biological malfunctions can give rise to symptoms of post-traumatic stress disorder (PTSD)—insight that might one day lead to more targeted treatments. In the meantime they are also exploring the use of biomarkers—hallmark variations in hormones, genes, enzymes and brain function—to apply existing therapies more effectively. “Trauma exposure can result in enduring biological changes that depend on an individual’s life history, age, gender and a host of other factors,” says Rachel Yehuda, a neuroscientist at Mount Sinai Hospital in New York City. “We must capitalize on this heterogeneity in the service of individualizing treatment approaches rather than insisting that one size fits all.” Indeed, not all patients get well by way of the most popular forms of therapy. One widely recommended treatment, cognitive behavioral therapy (CBT), typically helps only half of the patients who try it. In 2008 Richard Bryant, a professor of psychology at the University of New South Wales in Australia, and his colleagues attempted to identify that half up front. Before CBT they took brain scans using functional MRI of 14 subjects while showing them photographs of frightening faces. Seven people—the same who later failed to improve—showed greater than normal activity in brain regions associated with experiencing fear: the amygdala and the ventral anterior cingulate cortex. In another study Bryant found that the people who did benefit from CBT began treatment with larger rostral anterior cingulate cortices. Both animal and human studies have linked this brain area to “extinction,” the psychological process by which we unlearn conditioned responses, including fear. © 2015 Scientific American
By LISA FELDMAN BARRETT OUR senses appear to show us the world the way it truly is, but they are easily deceived. For example, if you listen to a recorded symphony through stereo speakers that are placed exactly right, the orchestra will sound like it’s inside your head. Obviously that isn’t the case. But suppose you completely trusted your senses. You might find yourself asking well-meaning but preposterous scientific questions like “Where in the brain is the woodwinds section located?” A more reasonable approach is not to ask a where question but a how question: How does the brain construct this experience of hearing the orchestra in your head? I have just set the stage to dispel a major misconception about emotions. Most people, including many scientists, believe that emotions are distinct, locatable entities inside us — but they’re not. Searching for emotions in this form is as misguided as looking for cerebral clarinets and oboes. Of course, we experience anger, happiness, surprise and other emotions as clear and identifiable states of being. This seems to imply that each emotion has an underlying property or “essence” in the brain or body. Perhaps an annoying co-worker triggers your “anger neurons,” so your blood pressure rises; you scowl, yell and feel the heat of fury. Or the loss of a loved one triggers your “sadness neurons,” so your stomach aches; you pout, feel despair and cry. Or an alarming news story triggers your “fear neurons,” so your heart races; you freeze and feel a flash of dread. Such characteristics are thought to be the unique biological “fingerprints” of each emotion. Scientists and technology companies spend enormous amounts of time and money trying to locate these fingerprints. They hope someday to identify your emotions from your facial muscle movements, your body changes and your brain’s electrical signals. © 2015 The New York Times Company
Link ID: 21254 - Posted: 08.02.2015
Mo Costandi When we say that we are “in pain”, we usually mean that an injured body part is hurting us. But the phenomenon we call pain consists of more than just physical sensations, and often has mental and emotional aspects, too. Pain signals entering the black box of the brain can be subjected further processing, and these hidden thought processes can alter the way we perceive them. We still know very little about these non-physical aspects of pain, or about the brain processes responsible for them. We do know, however, that learning and mental imagery can both diminish and enhance the experience of felt pain. Two new studies now extend these findings – one shows that subliminal learning can also alter pain responses, and the other explains how mental imagery can do so. It’s well known that simple associative learning procedures can alter responses to pain. For example, newborn babies who have diabetic mothers and are repeatedly exposed to heel pricks in the first few days of life exhibit larger pain responses during subsequent blood tests than healthy infants. Learning also appears to explain the placebo effect, and why it is often so variable. Several years ago, Karin Jensen, who is now at Harvard Medical School, and her colleagues showed that subliminal cues can reactivate consciously-learned associations to either enhance or diminish pain responses. In their latest study, the researchers set out to determine the extent to which this type of learning can occur non-consciously. © 2015 Guardian News and Media Limited
By Bret Stetka The brain is extraordinarily good at alerting us to threats. Loud noises, noxious smells, approaching predators: they all send electrical impulses buzzing down our sensory neurons, pinging our brain’s fear circuitry and, in some cases, causing us to fight or flee. The brain is also adept at knowing when an initially threatening or startling stimulus turns out to be harmless or resolved. But sometimes this system fails and unpleasant associations stick around, a malfunction thought to be at the root of post-traumatic stress disorder (PTSD). New research has identified a neuronal circuit responsible for the brain’s ability to purge bad memories, findings that could have implications for treating PTSD and other anxiety disorders. Like most emotions, fear is neurologically complicated. But previous work has consistently implicated two specific areas of the brain as contributing to and regulating fear responses. The amygdala, two small arcs of brain tissue deep beneath our temples, is involved in emotional reactions, and it flares with activity when we are scared. If a particular threat turns out to be harmless, a brain region behind the forehead called the prefrontal cortex steps in and the fright subsides. Our ability to extinguish painful memories is known to involve some sort of coordinated effort between the amygdala and the prefrontal cortex. The new study, led by Andrew Holmes at the National Institutes of Health, however, confirms that a working connection between the two brain regions is necessary to do away with fear. Normally mice that repeatedly listen to a sound previously associated with a mild foot shock will learn that on its own the tone is harmless, and they will stop being afraid. Using optogenetic stimulation technology, or controlling specific neurons and animal behavior using light, the authors found that disrupting the amygdala–prefrontal cortex connection prevents mice from overcoming the negative association with the benign tone. In neurobiology speak, memory “extinction” fails to occur. They also found that the opposite is true—that stimulating the circuit results in increased extinction of fearful memories. © 2015 Scientific American
By Emily Underwood My childhood hamster, Hamlet, seemed pretty depressed. He didn’t seem to enjoy his colorful cage, complete with a tunnel, wheel, and ramp. The only thing he did with zest was gnaw at the plastic, trying to escape, which he eventually did. A few days later, my mother found him lying on the bathroom floor, dead. I have wondered ever since: Was Hamlet suicidal? Or was he simply displaying normal hamster behavior? Now, a new study suggests a scientific method for gauging hamsters’ emotional states. Hamster emotions don’t just baffle pet owners; they also bedevil scientists who use the fluffballs as subjects in their experiments. One of the most frustrating things about trying to study animal emotion in general is that you can’t take behaviors at face value. If a hamster runs madly on its wheel all night, for example, how do you know if it is running out of joy, or boredom? (Or just for the heck of it.) To bypass that problem, the researchers decided to measure something called judgment bias—essentially, the way that mood affects behavior and decision-making. As humans, our decisions are influenced by our emotions all the time—witness stress-eating, or revenge-shopping. Similar biases have been found in primates, rats, mice, and many other animals, but never before in hamsters. In the experiment, researchers split 30 Syrian hamsters into two groups. One group lived the high life, in cages bedecked with extra toys, ramps, bedding, and hammocks. The second group had the minimum in hamster hospitality, with some light bedding and a wheel. © 2015 American Association for the Advancement of Science.
Link ID: 21234 - Posted: 07.29.2015
By JULIE SCELFO Kathryn DeWitt conquered high school like a gold-medal decathlete. She ran track, represented her school at a statewide girls’ leadership program and took eight Advanced Placement tests, including one for which she independently prepared, forgoing the class. Expectations were high. Every day at 5 p.m. test scores and updated grades were posted online. Her mother would be the first to comment should her grade go down. “I would get home from track and she would say, ‘I see your grade dropped.’ I would say, ‘Mom, I think it’s a mistake.’ And she would say, ‘That’s what I thought.’ ” (The reason turned out to be typing errors. Ms. DeWitt graduated with straight A’s.) In her first two weeks on the University of Pennsylvania campus, she hustled. She joined a coed fraternity, signed up to tutor elementary school students and joined the same Christian group her parents had joined at their alma mater, Stanford. But having gained admittance off the wait list and surrounded by people with seemingly greater drive and ability, she had her first taste of self-doubt. “One friend was a world-class figure skater. Another was a winner of the Intel science competition. Everyone around me was so spectacular and so amazing and I wanted to be just as amazing as they are.” Classmates seemed to have it all together. Every morning, the administration sent out an email blast highlighting faculty and student accomplishments. Some women attended class wearing full makeup. Ms. DeWitt had acne. They talked about their fantastic internships. She was still focused on the week’s homework. Friends’ lives, as told through selfies, showed them having more fun, making more friends and going to better parties. Even the meals they posted to Instagram looked more delicious. Her confidence took another hit when she glanced at the cellphone screen of a male student sitting next to her who was texting that he would “rather jump out of a plane” than talk to his seatmate. © 2015 The New York Times Company
By Ariana Eunjung Cha The Defense Advanced Research Projects Agency funds a lot of weird stuff, and in recent years more and more of it has been about the brain. Its signature work in this field is in brain-computer interfaces and goes back several decades to its Biocybernetics program, which sought to enable direct communication between humans and machines. In 2013, DARPA made headlines when it announced that it intended to spend more than $70 million over five years to take its research to the next level by developing an implant that could help restore function or memory in people with neuropsychiatric issues. Less known is DARPA's Narrative Networks (or N2) project which aims to better understand how stories — or narratives — influence human behavior and to develop a set of tools that can help facilitate faster and better communication of information. "Narratives exert a powerful influence on human thoughts, emotions and behavior and can be particularly important in security contexts," DARPA researchers explained in a paper published in the Journal of Neuroscience Methods in April. They added that "in conflict resolution and counterterrorism scenarios, detecting the neural response underlying empathy induced by stories is of critical importance." This is where the work on the Hitchcock movies comes in. Researchers at the Georgia Institute of Technology recruited undergraduates to be hooked up to MRI machines and watch movie clips that were roughly three minutes long. The excerpts all featured a character facing a potential negative outcome and were taken from suspenseful movies, including three Alfred Hitchcock flicks as well as "Alien," "Misery," "Munich" and "Cliffhanger," among others.
By Claire Asher City folk have a reputation for being less friendly than their rural counterparts, and the same appears to be true for garden birds. Urban song sparrows (Melospiza melodia, pictured) are more aggressive toward their neighbors than are sparrows out in the country, researchers report this month in Behavioral Ecology. But whereras the temperament of human city-dwellers is often attributed to the sheer density of people, this isn’t the case for sparrows. The team measured birds’ responses to recordings of another male’s song, noting how often males approached or attacked the speakers, and found that aggression depended not on the density of sparrows, but on the availability of food in the environment. Counterintuitively, male sparrows responded more aggressively in the city, where there tends to be more food, and rural birds became more aggressive when provided with food supplements. The authors explain that the sparrows defend food-rich, high-quality territories more aggressively, but it isn’t clear whether this is an offensive or a defensive strategy; city birds may be more aggressive because a territory with more food is more valuable to them, or because their abundant resources attract more thieves. © 2015 American Association for the Advancement of Science.
Link ID: 21221 - Posted: 07.27.2015
Sara Reardon After years of disappointment, clinical-trial results released on 22 July suggest that antibody treatments may produce small improvements in people with Alzheimer’s disease. The drugs — Eli Lilly’s solanezumab and Biogen’s aducanumab — target the amyloid-β protein that accumulates in the brains of people with Alzheimer’s. Many researchers question whether the findings will hold up, given that antibody drugs against amyloid have failed in every previous test against the disease. Details of the results were presented at the Alzheimer's Association International Conference in Washington DC. Lilly, of Indianapolis, Indiana, says that in a trial with 440 participants, solanezumab seemed to slow the cognitive decline of people with mild Alzheimer’s by about 30%. The loss of mental acuity in these patients over 18 months was equivalent to the deterioration that participants with a similar level of Alzheimer's disease in a placebo group experienced in just 12 months. Lilly snatched this small victory from the jaws of defeat. In 2012, the company reported no difference between patients who had taken solanezumab for 18 months and those who had received a placebo. But when the company reanalyzed that trial it found a slight improvement in participants whose symptoms were mild when the trial began. Lilly continued the test for six months and began giving solanezumab to the 440-member control group, whose disease was by then more advanced. © 2015 Nature Publishing Group,
By Gretchen Reynolds A walk in the park may soothe the mind and, in the process, change the workings of our brains in ways that improve our mental health, according to an interesting new study of the physical effects on the brain of visiting nature. Most of us today live in cities and spend far less time outside in green, natural spaces than people did several generations ago. City dwellers also have a higher risk for anxiety, depression and other mental illnesses than people living outside urban centers, studies show. These developments seem to be linked to some extent, according to a growing body of research. Various studies have found that urban dwellers with little access to green spaces have a higher incidence of psychological problems than people living near parks and that city dwellers who visit natural environments have lower levels of stress hormones immediately afterward than people who have not recently been outside. But just how a visit to a park or other green space might alter mood has been unclear. Does experiencing nature actually change our brains in some way that affects our emotional health? That possibility intrigued Gregory Bratman, a graduate student at the Emmett Interdisciplinary Program in Environment and Resources at Stanford University, who has been studying the psychological effects of urban living. In an earlier study published last month, he and his colleagues found that volunteers who walked briefly through a lush, green portion of the Stanford campus were more attentive and happier afterward than volunteers who strolled for the same amount of time near heavy traffic. But that study did not examine the neurological mechanisms that might underlie the effects of being outside in nature. So for the new study, which was published last week in Proceedings of the National Academy of Sciences, Mr. Bratman and his collaborators decided to closely scrutinize what effect a walk might have on a person’s tendency to brood. © 2015 The New York Times Company
By James Gallagher Health editor, BBC News website Irregular sleeping patterns have been "unequivocally" shown to lead to cancer in tests on mice, a study suggests. The report, in Current Biology, lends weight to concerns about the damaging impact of shift work on health. The researchers said women with a family risk of breast cancer should never work shifts, but cautioned that further tests in people were needed. The data also indicated the animals were 20% heavier despite eating the same amount of food. Studies in people have often suggested a higher risk of diseases such as breast cancer in shift workers and flight attendants. One argument is disrupting the body's internal rhythm - or body clock - increases the risk of disease. However, the link is uncertain because the type of person who works shifts may also be more likely to develop cancer due to factors such as social class, activity levels or the amount of vitamin D they get. Mice prone to developing breast cancer had their body clock delayed by 12 hours every week for a year. Normally they had tumours after 50 weeks - but with regular disruption to their sleeping patterns, the tumours appeared eight weeks earlier. The report said: "This is the first study that unequivocally shows a link between chronic light-dark inversions and breast cancer development." Interpreting the consequences for humans is fraught with difficulty, but the researchers guesstimated the equivalent effect could be an extra 10kg (1st 8lb) of body weight or for at-risk women getting cancer about five years earlier. "If you had a situation where a family is at risk for breast cancer, I would certainly advise those people not to work as a flight attendant or to do shift work," one of the researchers, Gijsbetus van der Horst, from the Erasmus University Medical Centre, in the Netherlands, said. © 2015 BBC.
By NANCY L. SEGAL, AARON T. GOETZ and ALBERTO C. MALDONADO SEVERAL years ago, while browsing the campus bookstore, one of us, Professor Segal, encountered a display table filled with Squirtles. A Squirtle is a plush-toy turtle manufactured by the company Russ Berrie. They were adorable and she couldn’t wait to take one home. Afterward, Professor Segal began wondering why this toy was so attractive and suspected that its large, round eyes played a major role. It’s well known that a preference for large eyes emerges in humans by 5 months of age. But the Squirtle was even more appealing than many of its big-eyed competitors. Was there something else about its eyes? Professor Segal consulted one of us, Professor Goetz, a colleague in evolutionary psychology, who suggested that because the Squirtle’s eyes were bordered in white, the cooperative eye hypothesis might have answers. This hypothesis, developed by the Japanese researchers Hiromi Kobayashi and Shiro Kohshima, holds that the opaque white outer coating of the human eye, or sclera, evolved to assist communication between people by signaling the direction of their gaze. The clear visibility of the sclera is a uniquely human characteristic. Other primates, such as the African great apes, also track the gaze direction of others, yet their sclera are pigmented or, if white, not visible. The great apes appear to use head direction more than other cues when following another’s gaze. Do humans have an instinctive preference for the whites of eyes, thus explaining the allure of the Squirtle? We conducted a study, to be published this year in the journal Evolution and Human Behavior, that suggested that the answer was yes. First we had to make some stuffed animals. We used six specially designed sets of three or four animals each (three cats, three dogs, three octopuses, four elephants, four snails and four turtles). The animals within each set were identical except for the eyes, which varied with respect to the size, color and presence of sclera. © 2015 The New York Times Company
Link ID: 21191 - Posted: 07.20.2015