Chapter 15. Emotions, Aggression, and Stress

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By Gary Stix The emerging academic discipline of neuroethics has been driven, in part, by the recognition that introducing brain scans as legal evidence is fraught with peril. Most neuroscientists think that a brain scan is unable to provide an accurate representation of the state of mind of a defendant or determine whether his frontal lobes predispose to some wanton action. The consensus view holds that studying spots on the wrinkled cerebral cortex that are bigger or smaller in some criminal offenders may hint at overarching insights into the roots of violence, but lack the requisite specificity to be used as evidence in any individual case. “I believe that our behavior is a production of activity in our brain circuits,” Steven E. Hyman of the Broad Institute of Harvard and MIT told a session at the American Association for the Advancement of Science’s annual meeting earlier this year. “But I would never tell a parole board to decide whether to release somebody or hold on to somebody, based on their brain scan as an individual, because I can’t tell what are the causal factors in that individual.” It doesn’t seem to really matter, though, what academic experts believe about the advisability of brain scans as Exhibit One at trial. The entry of neuroscience in the courtroom has already begun, big time. The introduction of a brain scan in a legal case was once enough to generate local headlines. No more. Hundreds of legal opinions each year have begun to invoke the science of mind and brain to bolster legal arguments—references not only to brain scans, but a range of studies that show that the amygdala is implicated in this or the anterior cingulate cortex is at fault for that. The legal establishment, in short, has begun a love affair with all things brain. © 2013 Scientific American

Keyword: Consciousness; Aggression
Link ID: 18955 - Posted: 11.21.2013

By JOHN TIERNEY How aggressive is the human female? When the anthropologist Sarah B. Hrdy surveyed the research literature three decades ago, she concluded that “the competitive component in the nature of women remains anecdotal, intuitively sensed, but not confirmed by science.” Science has come a long way since then, as Dr. Hrdy notes in her introduction to a recent issue of Philosophical Transactions of the Royal Society devoted entirely to the topic of female aggression. She credits the “stunning” amount of new evidence partly to better research techniques and partly to the entry of so many women into scientific fields once dominated by men. The existence of female competition may seem obvious to anyone who has been in a high-school cafeteria or a singles bar, but analyzing it has been difficult because it tends be more subtle and indirect (and a lot less violent) than the male variety. Now that researchers have been looking more closely, they say that this “intrasexual competition” is the most important factor explaining the pressures that young women feel to meet standards of sexual conduct and physical appearance. The old doubts about female competitiveness derived partly from an evolutionary analysis of the reproductive odds in ancient polygynous societies in which some men were left single because dominant males had multiple wives. So men had to compete to have a chance of reproducing, whereas virtually all women were assured of it. But even in those societies, women were not passive trophies for victorious males. They had their own incentives to compete with one another for more desirable partners and more resources for their children. And now that most people live in monogamous societies, most women face the same odds as men. In fact, they face tougher odds in some places, like the many college campuses with more women than men. © 2013 The New York Times Company

Keyword: Aggression; Aggression
Link ID: 18940 - Posted: 11.19.2013

by Erika Engelhaupt When I was in graduate school, I once gassed out my lab with the smell of death. I was studying the products of plant decomposition, and I had placed copious quantities of duckweed into large tubs and let the mix decompose for a few weeks. Duckweed is a small floating aquatic plant; it looks harmless enough. But when I dragged my tubs into the lab and set up a pump and filtration system, all hell broke loose. The filter clogged, the back pressure threw the hose off the pump, and a spray of decomposed mess flew all over a poor professor who had come in to help. For the rest of the day, he smelled like a pile of dead raccoons. That day, I learned about cadaverine and putrescine. These two molecules are produced during the decomposition of proteins, when the amino acids lysine and ornithine break down, and they are largely responsible for the smell of rotting flesh. My mistake in the lab was to think that rotting plants are more innocuous than rotting animals. Duckweed, it turns out, has such high protein levels that it’s used as animal feed, and those proteins, like any proteins, can create a deathly stench. The smells of cadaverine and putrescine tend to provoke a strong reaction (as I learned once the duckweed stench subsided and my labmates were able to return to the lab). But not every animal finds the odors disgusting. Carrion flies, rats and other animals that eat or lay eggs in dead things are attracted to the molecules. So researchers have started to look for exactly how animals tune in to these smells. Pinning down animals' odor detectors gives researchers a way to study aversion or attraction to certain objects. And understanding how these behavioral responses work will, I believe, help researchers clarify why humans feel the distinct emotion known as disgust. © Society for Science & the Public 2000 - 2013.

Keyword: Chemical Senses (Smell & Taste); Aggression
Link ID: 18939 - Posted: 11.16.2013

When President Obama announced his plan to explore the mysteries of the human brain seven months ago, it was long on ambition and short on details. Now some of the details are being sketched in. They will include efforts to restore lost memories in war veterans, create tools that let scientists study individual brain circuits and map the nervous system of the fruit fly. The Defense Advanced Projects Agency, or DARPA, which has committed more than $50 million to the effort, offered the clearest plan. The agency wants to focus on treatments for the sort of brain disorders affecting soldiers who served in Iraq and Afghanistan, according to , deputy director of . "That is our constituency," Ling said at a news conference at the Society for Neuroscience meeting in San Diego. A colored 3-D MRI scan of the brain's white matter pathways traces connections between cells in the cerebrum and the brainstem. So DARPA will be working on problems including PTSD and traumatic brain injuries, Ling says. In particular, the agency wants to help the soldier who has "a terribly damaged brain and has lost a significant amount of declarative memory," Ling said. "We would like to restore that memory." DARPA hopes to do that with an implanted device that will take over some functions of the brain's hippocampus, an area that's important to memory. The agency has already used a device that does this in rodents, Ling said, and the goal is to move on to people quickly. The agency plans to use the same approach that created a better in record time, Ling said. "We went from idea to prototype in 18 months," he says. This undated X-ray image from the Cleveland Clinic shows electrodes implanted in a patient's brain. The method, known as deep brain stimulation, has traditionally been used to treat diseases such as Parkinson's, but new research indicates it could be helpful for patients with obsessive-compulsive disorder. ©2013 NPR

Keyword: Stress; Aggression
Link ID: 18935 - Posted: 11.16.2013

by Jessica Griggs, San Diego Pregnant women may pass on the effects of stress to their fetus by way of bacterial changes in their vagina, suggests a study in mice. It may affect how well their baby's brain is equipped to deal with stress in adulthood. The bacteria in our body outnumber our own cells by about 10 to 1, with most of them found in our gut. Over the last few years, it has become clear that the bacterial ecosystem in our body – our microbiome – is essential for developing and maintaining a healthy immune system. Our gut bugs also help to prevent germs from invading our bodies, and help to absorb nutrients from food. A baby gets its first major dose of bacteria in life as it passes through its mother's birth canal. En route, the baby ingests the mother's vaginal microbes, which begin to colonise the newborn's gut. Chris Howerton, then at the University of Pennsylvania in Philadelphia, and his colleagues wanted to know if this initial population of bacteria is important in shaping a baby's neurological development, and whether that population is influenced by stress during pregnancy. The first step was to figure out what features of the mother's vaginal microbiome might be altered by stress, and then see if any of those changes were transmitted to the offspring's gut. © Copyright Reed Business Information Ltd

Keyword: Development of the Brain; Aggression
Link ID: 18934 - Posted: 11.16.2013

by Laura Sanders SAN DIEGO — When stress during pregnancy disrupts a growing baby’s brain, blame bacteria. Microbes take part in an elaborate chain reaction, a new study finds: First, stress changes the populations of bacteria dwelling in a pregnant mouse’s vagina; those changes then affect which bacteria colonize a newborn pup’s gut; and the altered gut bacteria change the newborn’s brain. The research, presented at the annual Society for Neuroscience meeting, may help explain how a stressful environment early in life can make a person more susceptible to disorders such as autism or schizophrenia. The finding also highlights the important and still mysterious ways that the bacteria living in bodies can influence the brain. “This is really fascinating and promising work,” said neuroscientist Cory Burghy of the University of Wisconsin–Madison. “I am excited to take a look at how these systems interact in humans,” she said. Stress during pregnancy dramatically shifts the mix of bacteria that dwell in the vagina, Christopher Howerton of the University of Pennsylvania reported November 11. The alarming odor of foxes, loud noise, physical restraints and other stressful situations during a mouse’s pregnancy changed the composition of its vaginal bacteria, he and his colleagues found. The population of helpful Lactobacillus bacteria, for instance, decreased after stress. And because newborn mouse pups populate their guts with bacteria dwelling in their mother’s birth canal, microbes from mom colonize the baby’s gut. Mice born to moms with lower levels of Lactobacillus in the vagina had lower levels of Lactobacillus in their guts soon after they were born, the team reported. © Society for Science & the Public 2000 - 2013

Keyword: Stress; Aggression
Link ID: 18927 - Posted: 11.14.2013

SAN DIEGO, CALIFORNIA—How do we recognize emotions in the facial expressions of others? A small, almond-shaped structure called the amygdala, located deep within the brain (yellow in image above), plays a key role, but exactly what it responds to is unclear. To learn more, neuroscientists implanted electrodes into the amygdalae of seven epileptic patients who were about to undergo brain surgery for their condition. They recorded the activity of 200 single amygdala neurons and determined how they responded while the patients viewed photographs of happy and fearful faces. The team found a subset of cells that distinguish between what the patients thought to be happy and fearful faces, even when they perceived ambiguous facial expressions incorrectly. (The team carefully manipulated some of the photos of fearful faces, so that some of the subjects perceived them as being neutral.) The findings, presented here yesterday at the 43rd annual meeting of the Society for Neuroscience, suggest that amygdala neurons respond to the subjective judgement of emotions in facial expressions, rather than the visual characteristics of faces that convey emotions. The scientists also found that the cellular responses persisted long after each of the photographs disappeared, further suggesting that the amygdala cooperates with other brain regions to create awareness of the emotional content of faces. Thus, when it comes to recognizing the facial expressions of others, what we think we see seems to be more important than what we actually see. © 2013 American Association for the Advancement of Science.

Keyword: Vision; Aggression
Link ID: 18910 - Posted: 11.12.2013

Ian Sample, science correspondent in San Diego Criminal courts in the United States are facing a surge in the number of defendants arguing that their brains were to blame for their crimes and relying on questionable scans and other controversial, unproven neuroscience, a legal expert who has advised the president has warned. Nita Farahany, a professor of law who sits on Barack Obama's bioethics advisory panel, told a Society for Neuroscience meeting in San Diego that those on trial were mounting ever more sophisticated defences that drew on neurological evidence in an effort to show they were not fully responsible for murderous or other criminal actions. Lawyers typically drew on brain scans and neuropsychological tests to reduce defendants' sentences, but in a substantial number of cases the evidence was used to try to clear defendants of all culpability. "What is novel is the use by criminal defendants to say, essentially, that my brain made me do it," Farahany said following an analysis of more than 1,500 judicial opinions from 2005 to 2012. The rise of so-called neurolaw cases has caused serious concerns in the country where brain science first appeared in murder cases. The supreme court has begun a review of how such evidence can be used in criminal cases. But legal and scientific experts nevertheless foresee the trend spreading to other countries, including the UK, and Farahany said she was expanding her work abroad. The survey even found cases where defendants had used neuroscience to argue that their confessions should be struck out because they were not competent to provide them. "When people introduce this evidence for competency, it has actually been relatively successful," Farahany said. © 2013 Guardian News and Media Limited

Keyword: Brain imaging; Aggression
Link ID: 18909 - Posted: 11.11.2013

by Guest Writer, Emilie Reas! My first trip to a haunted house is as vivid today as when I was 5 years old. As I made my way past a taunting witch and a rattling skeleton, my eyes fell upon a blood-soaked zombie. My heart raced, my throat swelled, and the tears began to flow. Even now, as a mature (ahem) adult, the ghosts and goblins don’t faze me. But those vacant zombie eyes and pale skin? Oh, the horror! My rational brain knows how irrational my fear is, yet still I shudder, gripped by the same terror that first overwhelmed me decades ago. Unsettling experiences occur daily that we easily brush off – a creepy movie, a turbulent plane ride, or a nip at your ankle by the neighbor’s dog. But occasionally, the fear sticks, establishing a permanent memory that can haunt us for years. At their mildest, such fear memories cause discomfort or embarrassment, but at their worst, they can be downright debilitating. Do spiders make you scream? Are you unable to speak in public without a trembling voice and hands? Maybe you suffered a traumatic accident that’s made you terrified to get back behind the wheel of a car. We’ve all experienced the disruptive effects of a fearful experience we just can’t shake. Yet scientists don’t fully understand why some traumatic events are fleeting, while others are stored as lasting memories. Past research has shown that particular areas of the brain, such as the anterior cingulate and insula, are active during fearful experiences, but also during many other situations, including while monitoring surroundings and emotions or paying attention to important information. Other regions, including the amygdala, hippocampus and prefrontal cortex, are more specialized to support memory for emotional experiences, as they play important roles in emotional processing, memory and attention. While it’s clear that establishing fear memories relies on cross-talk between these regions, it’s not known how they solidify fears into memory and determine which particular ones will endure for the long-term. © Society for Science & the Public 2000 - 2013

Keyword: Learning & Memory; Aggression
Link ID: 18902 - Posted: 11.09.2013

By Victoria Stern A trolley is hurtling down a track, and if nobody intervenes it will hit and kill five people. Psychologists use variations on this hypothetical situation to gauge people's gut reactions about morality. Here are three scenarios: The driver could switch the train to another track, on which one man stands. Should the driver reroute the trolley? Now suppose the trolley is driverless and you are a bystander. Should you hit a switch to divert the trolley so it hits the lone man? You are standing above the tracks on a bridge. You could stop the trolley and save the five people by pushing a large man to his death in front of the trolley. Would you push him? Most people say that the driver should reroute the train and that they would reroute the train with the switch but that they would not push the man to his death. This typical decision is associated with increased activity in the medial prefrontal cortex (green), which indicates a strong negative emotional reaction, as well as activity in the amygdala (red), which is involved in processing emotions and stressful events. © 2013 Scientific American

Keyword: Emotions; Aggression
Link ID: 18882 - Posted: 11.07.2013

By Brian Switek I’m going to ruin sea otters for you. Or at least I’m going to tarnish their reputation as some of the most charming little beasties in the seas. For as cute as they are while intertwining paws at an aquarium, frolicking among the wafting fronds of California kelp forests, or smashing sea urchins open with stones, some sea otters have developed the disturbing habit of humping and drowning baby seals. When I first heard about the behavior from a marine biologist friend of mine, I didn’t quite believe sea otters could be so diabolical. Maybe the bad behavior was just a rumor. But no, the strange sea otter attacks on baby seals are a reality and have even made their way into the technical literature. In 2010, California Department of Fish and Game biologist Heather Harris and colleagues reported 19 individual cases of male sea otters trying to mate with, and often fatally injuring, harbor seal pups in the Monterey Bay, Calif. area between 2000 and 2002 alone. Delivered in the scientific deadpan required of such papers, the Aquatic Mammals report attributes the incidents to three male sea otters “observed harassing, dragging, guarding, and copulating with harbor seals,” persisting for up to seven days after the otters killed the objects of their misguided advances. The ordeal must have been horrific for the seals. The victims that were necropsied by veterinarians had lesions around the nose, eyes, flippers, and genitals, including perforations in the vaginal and rectal tracts. A painful and confusing end for the poor pups. © 2013 The Slate Group, LLC.

Keyword: Sexual Behavior; Aggression
Link ID: 18877 - Posted: 11.06.2013

by Bethany Brookshire Most of us see a wagging dog’s tail and think it’s got to be a good sign. Wagging = welcome, right? Especially if it’s the kind of wag that’s knocking over small items. But it turns out that not all wags are equal, and some are a lot more welcoming than others. When I walked into my college biology course freshman year, we started out with a discussion of symmetry. Most animal are built with some symmetry, either radial or bilateral — radial like a starfish, bilateral like a human. Symmetry means things, like health or attractiveness. But it turns out that asymmetry can mean things too. And an asymmetrical behavior might mean some important things for dogs. Marcello Siniscalchi of the University of Bari Aldo Moro in Italy and colleagues decided to look at asymmetry in dog wags. They noticed that sometimes, dogs wag more to the right, usually when seeing their owner or something else happy. They wag more to the left when they see something like a dominant or unfamiliar dog. So the wag itself could represent the emotional state of the dog doing the wagging. But can the dogs seeing the wagging (the wagees) tell the difference? In a paper published October 31 in Current Biology, the authors found that they can. They used videos of a real dog or the silhouette of a dog wagging to the right (the wagging dog’s right, by the way) or to the left, and examined 43 other dogs as they watched (OK, they started with 56, but 13 didn’t pay attention), to see how the wagee reacted. The observing dogs wore a vest to monitor their heart rate, and were videotaped so behaviorists could look at their behaviors afterward. © Society for Science & the Public 2000 - 2013.

Keyword: Animal Communication; Aggression
Link ID: 18864 - Posted: 11.02.2013

By Jesse Bering Disgust, in its most familiar form, is our response to something vile in the world—spoiled food, a dirty floor or rats cavorting in the subway. It is a contamination-avoidance mechanism that evolved to help us make biologically adaptive decisions in the heat of the moment. Yet disgust has also come to have powerful symbolic elements. When left unchecked, these symbolic qualities can have devastating impacts on our mental states. Consider, for example, the often dramatized, heartbreaking image of a woman crouched in the corner of a shower and frantically trying to scrub her body clean after being raped. Empirical evidence supports the characterization. Seventy percent of female victims of sexual assault report a strong impulse to wash afterward, and a quarter of these continue to wash excessively up to three months later. For women, simply imagining an unwanted advance can turn on this moral-cleansing effect. Psychiatrist Nichole Fairbrother of the University of British Columbia Hospital and her colleagues looked more closely at the phenomenon of mental pollution in a study published in 2005. Two groups of female participants were told to close their eyes and picture being kissed. The members of one group were instructed to imagine being aggressively cornered and kissed against their will. The members of the other group were asked to envision themselves in a consensual embrace. Only those women in the coercive condition chose to wash up after the study. In many cases, it seems as though a person's sense of self has become contaminated. © 2013 Scientific American

Keyword: Emotions
Link ID: 18811 - Posted: 10.19.2013

by Bruce Bower Thomas Jefferson defended the right to pursue happiness in the Declaration of Independence. But that’s so 237 years ago. Many modern societies champion everyone’s right to be happy pretty much all the time. Good luck with that, says psychologist Joseph Forgas of the University of New South Wales in Sydney. A lack of close friends, unfulfilled financial dreams and other harsh realities leave many people feeling lonely and forlorn a lot of the time. But there’s a mental and social upside to occasional downers that often goes unappreciated. “Bad moods are seen in our happiness-focused culture as representing a problem, but we need to be aware that temporary, mild negative feelings have important benefits,” Forgas says. Growing evidence suggests that gloomy moods improve key types of thinking and behavior, Forgas asserts in a new review paper aptly titled “Don’t worry, be sad!” For good evolutionary reasons, positive and negative moods subtly recruit thinking styles suited to either benign or troubling situations, he says. Each way of dealing with current circumstances generally works well, if imperfectly. New and recent studies described by Forgas in the June Current Directions in Psychological Science illustrate some of the ways in which periods of sadness spontaneously recruit a detail-oriented, analytical thinking style. Morose moods have evolved as early-warning signs of problematic or dangerous situations that demand close attention, these reports suggest. © Society for Science & the Public 2000 - 2013.

Keyword: Emotions; Aggression
Link ID: 18810 - Posted: 10.19.2013

By Jason G. Goldman Scientists love yawning. No, that’s not quite right. Scientists love doing research on yawning. It seems to be of interest to folks in fields ranging from primatology to developmental psychology to psychopathology to animal behavior. If the notion of scientifically investigation the purpose of yawning makes you, well, yawn, then you’re missing one of the more interesting debates in the social cognition literature. To understand why yawning is about more than feeling tired or bored, we have to go back a few years. Once upon a time, scientists thought that yawning might be process through which the brain keeps itself cool (PDF). Yawning is associated with increases in blood pressure, and the consequential increase in blood flow might mean that the vascular system acts as a radiator, replacing the warm blood in the brain with cooler blood. It could also be that the deep inhalation of cold air during a yawn can, through convection, alter blood temperature which in turn could cool the brain. Even if it turns out that some yawns can be explained through purely physiological means, yawning is also contagious for humans and other species. If someone watches someone else yawning, they’ll be likely to yawn as well. That means that there is social component to yawning, and it might be related to empathy. It turns out that there’s a correlation between a person’s self-reported empathy and their susceptibility to reacting to a yawn contagion, and those who are more skilled at theory of mind tasks are also more likely (PDF) to yawn contagiously. © 2013 Scientific American

Keyword: Emotions; Aggression
Link ID: 18801 - Posted: 10.17.2013

By Sandra G. Boodman, Janet Ruddock was crushed: She had dreamed of greeting her first grandchild, and now that once-in-a-lifetime experience had been marred by the embarrassing problem that had derailed her life for nearly a decade. In June 2010, Ruddock, then 59, and her husband had flown to Vancouver, B.C., from Washington to meet their new grandson. But soon after they arrived, Ruddock’s in­trac­table sweating went into overdrive. As she sat in a rocking chair, perspiration drenched her head and upper body, soaking her shirt and dripping onto the 4-week-old infant. “I burst into tears,” Ruddock recalled. “All I can remember is the feeling that I’m wet, this poor baby’s wet and a moment you should always remember is ruined. You’re never going to get it back. “ For Ruddock, that event precipitated a suicidal depression. For the previous eight years she had undergone tests, taken drugs and endured the bafflement — and skepticism — of a parade of doctors she consulted about the extreme, unpredictable sweating that engulfed her head and upper body. After confiding her despair to a relative, she began seeing a psychiatrist. By chance, a few months later she learned about a woman whose experience mirrored her own and provided her a much-needed road map. “It’s a fascinoma,” said retired Washington internist Charles Abrams, using the medical slang for an unusual — or unusually interesting — case. “You usually hate for patients to come in and say, ‘I found this on the Internet,’ ” said Abrams, who treated Ruddock until his retirement last year. “But every once in a while, something is brought to your attention.” © 1996-2013 The Washington Post

Keyword: Miscellaneous
Link ID: 18787 - Posted: 10.15.2013

by Stephanie Pappas, LiveScience Apes orphaned by the African bushmeat trade lack the social savvy of apes raised by their mothers, a new study finds. The study links the emotional development of bonobos (Pan paniscus), one of humans' closest living relatives, with the ability to interact nicely with others, echoing how human emotions develop. Bonobos who are good at soothing themselves out of a bad mood are more likely to comfort other bonobos in distress, researchers report today (Oct. 14) in the journal Proceedings of the National Academy of Sciences. "By measuring the expression of distress and arousal in great apes, and how they cope, we were able to confirm that efficient emotion regulation is an essential part of empathy," study researcher Frans de Waal, of Emory University's National Primate Research Center, said in a statement. PHOTOS: How Santino, the Chimp, Attacks Visitors Though animal emotions "have long been scientifically taboo," de Waal said, he and his colleagues suspected that emotions might have evolved similarly before the bonobo and human lines split about 6 million years ago. The researchers observed juvenile bonobos at a sanctuary near Kinshasa in the Democratic Republic of the Congo. They watched as the young primates fought, threw tantrums and comforted one another by hugging or stroking. (See Video of a Bonobo Hug) In 373 post-distress interactions (318 caused by fights and 55 caused by tantrums), the researchers found that the better a bonobo was at soothing his or her own emotions, the more likely he or she was to rush to aid a friend in need. A similar pattern is seen in human interactions, the researchers reported. © 2013 Discovery Communications, LLC.

Keyword: Emotions; Aggression
Link ID: 18785 - Posted: 10.15.2013

By Deborah Kotz / Globe Staff As much as you may hate hearing honking traffic or rumbling trains breaking up the silence while you drift off to sleep, can such irritating noises do serious damage to your health? That’s a question researchers have been trying to answer for years, and they’ve come a bit closer to finding out in a new study looking at the impact of airplane noise in those who live close to airports. Two new studies published in the British Medical Journal this week found that living in a home directly in the flight-path of low-flying planes was associated with an increased risk of being hospitalized for heart disease or a stroke. One study, conducted by Boston-based researchers, examined Medicare records from 6 million seniors living near 89 U.S. airports and found that every 10 decibel level increase in noise from planes that seniors were exposed was linked to a 3.5 percent higher hospitalization rate for heart disease. (About 6 percent of the study population was hospitalized for heart problems during 2009 when the data was collected.) The second study, performed by British researchers, found that folks living near London’s Heathrow airport who were regularly exposed to the greatest levels of noise from planes—greater than 63 decibels which is louder than the sounds of close conversation—were more than 20 percent more likely to be hospitalized for a stroke or for heart disease than those with the least noise exposure. Neither study could prove that the airport noise led to more hospitalizations, but researchers controlled for certain factors like air pollution and road traffic noise which could also raise heart and stroke risks. They couldn’t control for others like smoking habits or diet. © 2013 NY Times Co.

Keyword: Stress; Aggression
Link ID: 18779 - Posted: 10.12.2013

By Stephen L. Macknik and Susana Martinez-Conde Dennis Rogers is an unassuming guy. He's on the short side. And though muscular, he doesn't come across as the kind of towering Venice Beach, muscle-bound Arnold that you might expect from someone billed as the World's Strongest Man. Rather he has the kind of avuncular intensity you find in a great automobile mechanic—a mechanic who happens to be able to lift an engine with one hand while using the fingertips of the other hand to wrench the spark plugs out. Like it's nothing. Rogers, who has been known to keep two U.S. Air Force fighter planes from blasting away in opposite directions by holding them back with his bare hands, performed at the most recent Gathering for Gardner—a conference that celebrates the interests of one of Scientific American's greatest columnists, the late mathemagician Martin Gardner. We asked Rogers about the source of his incredible powers after the show, and we were surprised to learn that he did not know. Bill Amonette of the University of Houston–Clear Lake found that Rogers could recruit an abnormally high number of muscle fibers. But was this ability because of a freak genetic mutation? Another possibility, which Rogers thinks is more likely, is the way he processes pain when he strains those muscles. What if, instead of superpowered muscles, Rogers has a normal—though extremely well exercised—body, and his abilities arise because he can withstand more pain than most mere mortals? He claims that he does feel pain and is actually scared of dentists. In fact, during one stunt in which he held back four souped-up Harley motorbikes with straps, he bit down so hard he split a tooth from top to bottom. Rather than taking his chances at the dentist, he reached into his mouth, clamped his viselike fingertips onto the broken tooth, and extracted it, root and all. Rogers reasons that, unlike in the dentist's office—where he has no control over the pain that is inflicted on him—he has direct executive control over pain that he inflicts on himself. “I know it's coming, I have an idea of what to expect and I can decide to ignore it,” he says. © 2013 Scientific American

Keyword: Pain & Touch; Aggression
Link ID: 18766 - Posted: 10.09.2013

by Colin Barras Male marsupial mice just don't know when to stop. For Antechinus stuartii, their debut breeding season is so frenetic and stressful that they drop dead at the end of it from exhaustion or disease. It may be the females of the species that are driving this self-destructive behaviour. Suicidal breeding, known as semelparity, is seen in several marsupials. This is likely linked to short breeding seasons and the fact that the marsupial mice only breed once a year. It is not clear why this is, but it may be that females can only breed when the population of their insect prey reaches its peak. A year is a long and dangerous time for a small animal, so under these circumstances males might do best to pump all their resources into a single breeding season. To test this idea, Diana Fisher of the University of Queensland in St Lucia, Australia, and her colleagues tracked how insect abundance changed with the seasons in the marsupials' home forests. Sure enough, they found that the marsupials' breeding seasons were shortest where insect abundance followed a predictable annual pattern. But the insects are not the whole explanation. It turns out that females do sometimes survive the year and breed again. So why do the males always die? The key factor is that the females are highly promiscuous, says Fisher. Coupled with the short breeding season, this leads to intense competition between males. "Males that exert extreme effort in this short time are at an advantage." © Copyright Reed Business Information Ltd.

Keyword: Stress; Aggression
Link ID: 18758 - Posted: 10.08.2013