Links for Keyword: Aggression

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By Kate Shaw Early one morning I caught sight of Morpheus, silhouetted against a pink African dawn. Her long, sloping neck was stretched out as she loped away from me, disappearing over a hill. I followed her to a nearby plain and was met with the unmistakable sound of a group of hyenas squabbling over a carcass. Morpheus entered the fray, first lunging at a smaller male on her right. A moment later, she looked up briefly, her nose and mouth covered in blood, then turned and snapped at a hyena feeding nearby. I’m intimately acquainted with Morpheus and these other hyenas because they have been studied for more than twenty years by various members of the lab where I did my Ph.D. research; I’ve staked these hyenas out at dens for hours on end and followed them as they raced across open plains. From watching these animals, we’ve learned about hyenas’ social system, their physiology, and the conservation challenges they face. But to me, it’s the aggression that is the most fascinating thing about hyenas. It’s rule-based and constrained by specific social norms, but at the same time, it’s incredibly primal and ruthless. Studying aggression has helped us understand what makes hyenas tick, offering us a glimpse into the evolutionary pressures that have made them one of the most unusual and misunderstood species in the animal kingdom. For more than 1000 years, people believed that hyenas were hermaphrodites, since female hyenas have long, fully-erectile pseudopenises that mimic male genitalia. Seeing a hyena play the role of mom while sporting what looks like a penis would bewilder even an astute naturalist. Not only do female hyenas look like males, they are also the more aggressive and socially dominant sex, exhibiting aggression more than three times more often than male hyenas do. © 2012 Scientific American

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 17560 - Posted: 12.01.2012

By Caroline Parkinson Health editor, BBC News website The brains of teenage girls with behavioural disorders are different to those of their peers, UK researchers have found. The Journal of Child Psychology and Psychiatry study of 40 girls revealed differences in the structure of areas linked to empathy and emotions. Previous work has found similar results in boys. Experts suggest it may be possible to use scans to spot problems early, then offer social or psychological help. An estimated five in every 100 teenagers in the UK are classed as having a conduct disorder. It is a psychiatric condition which leads people to behave in aggressive and anti-social ways, and which can increase the risk of mental and physical health problems in adulthood. Rates have risen significantly among adolescent girls in recent years, while levels in males have remained about the same. In this study, funded by the Wellcome Trust and Medical Research Council, UK and Italian researchers conducted brain scans of 22 teenage girls who had conduct disorder and compared them with scans of 20 who did not. BBC © 2012

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 17402 - Posted: 10.22.2012

Young people who sustain brain injuries are more likely to commit crimes and end up in prison, research suggests. The University of Exeter study says such injuries can lead maturing brains to "misfire", affecting judgement and the ability to control impulses. It calls for greater monitoring and treatment to prevent later problems. The findings echo a separate report by the Children's Commissioner for England on the impact of injuries on maturing brains and the social consequences. In the report, Repairing Shattered Lives, Professor Huw Williams from the University of Exeter's Centre for Clinical Neuropsychology Research, describes traumatic brain injury as a "silent epidemic". It is said to occur most frequently among children and young people who have fallen over or been playing sport, as well as those involved in fights or road accidents. The consequences can include loss of memory, with the report citing international research which indicates the level of brain injuries among offenders is much higher than in the general population. A survey of 200 adult male prisoners in Britain found 60% claimed to have suffered a head injury, it notes. The report acknowledges there may be underlying risk factors for brain injury and offending behaviour but says improving treatment and introducing screening for young offenders would deliver significant benefits in terms of reducing crime and saving public money. BBC © 2012

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 15: Language and Our Divided Brain
Link ID: 17398 - Posted: 10.20.2012

By Jason G. Goldman When my brother and I were young, we were very careful to share the last bit of dessert equally. It’s not that we were particularly magnanimous. In their wisdom, my parents instituted a rule in our house: one of us would divide the snack in half, and the other would select his half. “You cut, I choose” was a common phrase in the Goldman household throughout the 1990s. The rule ensured that we’d each be as equitable as possible when in the role of divider. The kitchen ruler was retrieved on more than one occasion. If I thought I could have gotten away with scarfing down the last cookie without him noticing, I’m sure I would have done it. And I would not have been sorry. Imagine, however, what would have happened if my brother had decided to keep the entire last cookie for himself and run into the living room with it. Here’s one way he might have kept me from snatching my fair share of the snack: find a decent hiding spot, and if I got too close, he could run back into the kitchen. Once back in the kitchen, if I got too close to him, he could have gotten up and run back to the living room. This is called a “stimulus-response rule.” Eventually, being the bright child that I was, I would have caught onto the pattern and found a way to block his path from one room to the other, increasing the chance of getting some of the dessert. Here’s a better method that my brother could use to protect his treat: keep his eyes on me the entire time, always moving away from me so that the distance between us was, on average, fixed. If I go right, he goes left. If I move towards him, he backs up. Short of backing him into a corner, my efforts would be futile. That’s because instead of using a small set of predictable actions, my brother could call upon a wider range of behaviors. Its much harder for a thief to learn how you protect your food if your behaviors are variable than if they are predictable. This is called a “cybernetic rule.” © 2012 Scientific American

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 17337 - Posted: 10.06.2012

By Melinda Wenner Moyer Read any Web forum, and you'll agree: people are meaner online than in “real life.” Psychologists have largely blamed this disinhibition on anonymity and invisibility: when you're online, no one knows who you are or what you look like. A new study in Computers in Human Behavior, however, suggests that above and beyond anything else, we're nasty on the Internet because we don't make eye contact with our compatriots. Researchers at the University of Haifa in Israel asked 71 pairs of college students who did not know one another to debate an issue over Instant Messenger and try to come up with an agreeable solution. The pairs, seated in different rooms, chatted in various conditions: some were asked to share personal, identifying details; others could see side views of their partner's body through webcams; and others were asked to maintain near-constant eye contact with the aid of close-up cameras attached to the top of their computer. Far more than anonymity or invisibility, whether or not the subjects had to look into their partner's eyes predicted how mean they were. When their eyes were hidden, participants were twice as likely to be hostile. Even if the subjects were both unrecognizable (with only their eyes on screen) and anonymous, they rarely made threats if they maintained eye contact. Although no one knows exactly why eye contact is so crucial, lead author and behavioral scientist Noam Lapidot-Lefler, now at the Max Stern Yezreel Valley College in Israel, notes that seeing a partner's eyes “helps you understand the other person's feelings, the signals that the person is trying to send you,” which fosters empathy and communication. © 2012 Scientific American,

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 17266 - Posted: 09.17.2012

Jeannine Stamatakis psychologist John Watson, the founder of behaviorism, once said, “Give me a dozen healthy infants, well formed, and my own specified world to bring them up in, and I'll guarantee to take any one at random and train him to become any type of specialist I might select.” If we take Watson's logic one step further, it may be possible to mold someone into a psychopath. Psychopathy, also called sociopathy, is defined by a lack of empathy, deceitfulness and complete selfishness. Current thinking is that although certain genes may predispose people toward psychopathy, their environment seems to provide the ultimate catalyst. Thus, a person who possesses the particular genes associated with this malady and is brought up in an abusive or neglectful household will be at a higher risk of exhibiting the traits associated with this disorder. Severe trauma to specific regions of the brain can cause a person to undergo marked personality changes, such as in the famous case of Phineas Gage. While working as a railroad construction foreman in Vermont in 1848, he survived an accident in which a large iron rod was driven through his head, damaging much of his brain's left frontal lobe. Although he did not become a sociopath, the reported effects on his personality and behavior were so profound that friends saw him as “no longer Gage.” An incident two decades ago supports the idea that brain trauma can lead to psychopathic behaviors. In 1991 convicted sex offender Phillip Garrido kidnapped 11-year-old Jaycee Dugard and kept her as a prisoner in his home for 18 years. Experts believe that Garrido experienced severe brain damage after a serious motorcycle accident as a teenager, which was compounded by intense drug use. Garrido's father said that his son had been a “good boy” as a child but that he had changed radically after the accident and had become unstable. © 2012 Scientific American,

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 15: Language and Our Divided Brain
Link ID: 17222 - Posted: 09.07.2012

By Bruce Bower A callous, manipulative psychopath convicted of a brutal crime can count on a long prison stint. But a judge may issue a slightly shorter sentence if presented with a biological explanation for the criminal’s psychopathic personality. Supplying judges with scientific evidence about suspected brain deficits in psychopathy led to a reduction in prison sentences from about 14 years to 13 years, researchers report in the Aug. 17 Science. The results come from a nationwide, online survey of state judges given a hypothetical scenario about a psychopath convicted of what lawyers call aggravated battery. Judges taking the survey tended to view psychopathic criminals as dangerous, whether or not scientific evidence was introduced, say psychologist Lisa Aspinwall, lawyer Teneille Brown and philosopher James Tabery, all of the University of Utah in Salt Lake City. A hypothetical psychopath in the new study got sent to the slammer for longer than the average nine-year sentence given to non-psychopaths found guilty of aggravated battery in real courts. Aspinwall and her colleagues informed judges that clinicians use psychopathy — which is not an official psychiatric diagnosis — to refer to individuals who are impulsive, emotionally shallow, outwardly charming, lacking in empathy or remorse, chronic liars and callous manipulators (SN: 12/9/06, p. 379). Judges were told that psychopathy is incurable. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 17178 - Posted: 08.18.2012

By Winnie Yu If you want to keep your cool, you might want to pass up those greasy wings and gooey dessert. A new study from the University of California, San Diego, suggests that people whose diets are higher in trans fats are more prone to aggression. Trans fats, or hydrogenated oils, have made the news in recent years because studies have strongly linked them to heart disease and cancer, and some locales have passed laws restricting their use. They are still common, however, in restaurant food and many grocery items. Beatrice Golomb, a physician and associate professor of medicine at U.C. San Diego, wondered if trans fats might affect behavior, after noting how they interact with a type of healthy fat. Past studies found that docosahexaenoic acid—or DHA, a long-chain omega-3 fatty acid—has a calming, antidepressant effect. Trans fats disrupt the chemical process that leads to the conversion of fatty acids into DHA, which led Golomb to suspect that trans fats might be linked to aggression. Her study, which was published in March in PLoS ONE, involved 1,018 men and women older than 20 who filled out a food questionnaire and several other surveys that measure impatience, irritability and aggression. Even after considering other influences, Golomb's team found a strong link between the intake of trans fats and aggression. “Trans-fatty acids were a more consistent predictor of aggression than some traditional risk factors such as age, male sex, education and smoking,” Golomb says. The findings were consistent across both sexes and across all ages, ethnicities and socioeconomic groups. © 2012 Scientific American

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 17110 - Posted: 08.01.2012

by Amy West Many deep-sea squid dispel an ink cloud to flee a predator, but one species goes a step farther: It ensures a getaway by counterattacking and then ditching the tips of its arms. These detached bits can continue to twitch and emit bioluminescent light—likely providing a vital distraction. By catching this strange maneuver on camera, scientists have established Octopoteuthis deletron as the only known squid to drop portions of its arms in self-defense, much as lizards drop their tails before escaping. O. deletron inhabits depths of 500 to 600 meters. Little is known about the biology of these gelatinous deep-dwellers, but recently they have begun to yield their secrets—including some bizarre mating behavior—thanks to powerful video cameras mounted on robotic submersibles operated by researchers at Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, California. Viewing some of this footage, Stephanie Bush, a postdoctoral fellow at the University of Rhode Island, Kingston, noticed many individuals with arms of different lengths, and suspected that these cephalopods lost their arms during an attack. To investigate, Bush collaborated with researchers at MBARI. With a bit of luck, the team found squid off the coast of California, and tried poking them with the control arm of the submersible. The creatures attacked the vehicle but never held on, perhaps because they couldn't grip its smooth metal surface, Bush says. Eventually, the researchers resorted to attaching the bottle-brush they used to wash their laboratory glassware to the submersible. When they nudged the next squid they encountered, the squid attacked the brush and immediately left behind parts of two arms. Fortunately the team caught the action with a high-resolution camera (see video). As the scientists erupted into cheers in the control room, Bush says she wondered why she hadn't tried this earlier. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 17105 - Posted: 07.30.2012

by Sarah C. P. Williams To escape a hungry wolf, a sheep doesn't have to outrun the wolf, just the other sheep in its flock. Many researchers think that such selfish behavior, not cooperation for the benefit of the whole crowd, shapes the movements of groups of animals. But the decades-old "selfish herd theory" has been hard to back up with data. Now, a detailed analysis of how a flock of sheep moves to avoid a sheepdog has found that the theory holds true. Each sheep heads to safety in the center of the flock, rather than running directly away from the dog. "It's really difficult to measure 2D spatial information on large animals in the wild," says biologist Theodore Stankowich of the University of Massachusetts, Amherst, who was not involved in the new work. "They've taken advantage of a unique opportunity to work with the sheep to answer these types of questions in a controlled environment." Studies on seals, crabs, and pigeons have shown that those animals seem to herd for selfish reasons, but the data have often been crude. Biologist Andrew King and colleagues at the Royal Veterinary College of the University of London attached GPS backpacks to 46 sheep and to a trained Australian Kelpie dog. When they released the dog to herd the sheep, they recorded the location of each animal every second. Then, they analyzed the data to determine what factors influenced each sheep's path. The movements of the sheep, the researchers reveal today online in Current Biology, could be best predicted by the center of the flock. Rather than run in a line away from the dog, scatter in all directions, or follow their nearest neighbors, the sheep all hurried toward the flock's center. The sheep began to converge when the dog was 70 meters away. Even as the flock as a whole moved, each sheep continuously competed to be as near the middle as possible. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 17079 - Posted: 07.24.2012

By Larry Greenemeier Shortly after moviegoers had settled in to watch a midnight premier of The Dark Night Rises on Friday morning, a heavily armed gunman entered the Aurora, Colo., theater through an emergency exit and opened fire. In just a few minutes the assailant shot more than 60 children and adults—killing at least a dozen—before police arrested him outside the theater. This massacre was the only latest in a string of eerily similar incidents in recent years involving the mass murder of civilians, spectators and bystanders by an individual with a firearm and a frightening lack of regard over its use. In April 2007 32 people were shot to death and 17 injured on the campus of Virginia Polytechnic Institute and State University in Blacksburg, Va., by a former student. In January 2011, former U.S. Rep. Gabrielle Giffords was shot in the head by an assailant who killed six people during an attack outside a Tucson supermarket. Just a few months ago a gunman killed seven people at Oikos University in Oakland, Calif. In each of these and other similar cases, the lone assailant who was either captured or found dead at the scene of the crime matched a particular profile—a disgruntled loner with grievances against societal institutions and who displayed an abhorrent inability or unwillingness to exercise control over violent impulses. Following the attempted assassination of Giffords, Scientific American spoke with Marco Iacoboni, a University of California, Los Angeles, professor of psychiatry and biobehavioral sciences and director of the school’s Transcranial Magnetic Stimulation Laboratory, about why some individuals act on their violent thoughts whereas others do not. Although details about the life of University of Colorado neuroscience Ph.D. student James Holmes, arrested for the Aurora shootings, are still being uncovered, several of Iacoboni’s observations about accused Giffords gunman Jared Lee Loughner seem apt to shed some light on the violence that recent took place Friday morning. © 2012 Scientific American,

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 14: Attention and Consciousness
Link ID: 17072 - Posted: 07.21.2012

By Susan Milius OTTAWA — Larval fruit flies, supposedly relentless devourers of rotting fruit, at times leave their regular laboratory food to stalk, kill and group-cannibalize some of their older, fatter fellows, scientists report. This predatory cannibalism shows up in Drosophila melanogaster, the fly species that generations of biologists have grown in untold numbers, Roshan Vijendravarma of the University of Lausanne in Switzerland reported July 6 at the Evolution Ottawa scientific congress. He and Lausanne colleagues documented the behavior in both Canton S fruit flies, a strain raised in labs for more than six decades, and the Valais strain, brought into culture only in the last two years. Because fruit fly genetics is known in such detail, Vijendravarma said his discovery may allow researchers to study the evolution of predatory cannibalism at the DNA level. The closest reports Vijendravarma has found to what he’s witnessed describe larva of a different fruit fly, Drosophila hydei, dining on an already dead youngster of its own kind. What Vijendravarma reported is not just feeding on a happenstance free lunch, but hunting as well. He showed close-up videos of the dark, pronged mouthparts of a smaller larva scraping again and again against the wide, cream-colored body of a larger one. Finally the big larva’s body rips open, exposing softer flesh. Vijendravarma also showed photographs of clusters of small larvae side-by-side with their mouths against the flesh of a much larger one. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 17025 - Posted: 07.11.2012

by Michael Marshall Fancy getting into a fight? Here's a tip: don't. Even if you win you'll probably get hurt, and that will mean you have to spend weeks recovering when you could be doing something worthwhile, like curing cancer or having sex. Most animals know this instinctively and are reluctant to get into all-out fights. In particular, animals don't fight with members of other species. There's just no point: they aren't sexual rivals, and they have a different diet so they're not likely to steal food either. With some exceptions, including predator-prey struggles, animals only fight their direct competitors: members of their own species. Someone needs to tell the Dalmatian wall lizard about this unwritten rule – preferably through a megaphone from a safe distance. In field tests it picks fights with a neighbouring lizard species that poses no threat to it at all. Is it just a thug, or is there a good reason for its aggressive behaviour? Dalmatian wall lizards are named after the Dalmatia region of southern Croatia – as is the notoriously fecund breed of dog. As lizards go they look quite ordinary, measuring about 6 centimetres long, not counting their tails. They spend most of their time on the ground under vegetation or on low rocks. That keeps them separate from the neighbouring sharp-snouted rock lizards (Dalmatolacerta oxycephala), which tend to hang out on higher rocks where it's cooler. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 16923 - Posted: 06.16.2012

By Bruce Bower PORTLAND, Ore. — In a cooperative venture aimed at understanding the most uncooperative of acts, researchers studying different African communities of wild chimpanzees have pooled their data and found that the apes sometimes kill each other nearly everywhere they’ve been studied. Chimp homicides occurred most frequently in groups with the most adult males, anthropologist Michael Wilson of the University of Minnesota in Minneapolis reported April 12 at the American Association of Physical Anthropologists’ annual meeting. Wilson persuaded researchers at 10 wild chimp sites, containing a total of 17 communities, to contribute their findings on lethal attacks collected over the past several decades. Chimps spend most of their time in peaceful pursuits, such as playing, foraging and grooming each other. Yet researchers, beginning with Jane Goodall more than 40 years ago, have described occasional chimp homicides. Some investigators have speculated that these animals get lethally riled up by human intrusions, such as deforestation, hunting and feeding of chimps by eco-tourists. But the new study found that chimp communities with the most documented killings had no or only rare encounters with humans. Groups of males carried out most killings, and most victims were male adults and infants in neighboring communities. “The new findings suggest that killing is an evolved strategy, mainly for adult males to eliminate rivals and competitors for mates,” Wilson said. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 16646 - Posted: 04.14.2012

By Ferris Jabr Rhesus macaques, which are some of the best studied of all monkeys, establish hierarchies in their social groups. Whenever two macaques tussle over a piece of food, say, or the right to mate, the monkey with the higher rank usually wins. Primatologists have established that monkeys of a lower social status are generally more stressed out than their dominant peers—low-ranking monkeys have higher levels of stress hormones, for instance. But what about differences in gene activity? Does one’s social stature change how one’s genes are expressed. Yes, concludes a new study that used differences in gene expression to identify a monkey’s social status with around 80 percent accuracy. Jenny Tung of Duke University and her colleagues—including several collaborators at the Yerkes National Primate Research Center—studied 10 groups of adult female rhesus macaques made up of five females each. Researchers formed the groups one female at a time, which allowed them to carefully construct the social hierarchy: females introduced earlier generally assumed a higher rank. In this way, the scientists knew exactly which monkey held rank 1, 2, 3, 4 and 5 in each group. Tung and her colleagues collected blood samples from the rhesus macaques, isolated the white blood cells and analyzed the DNA in those cells. They found 987 genes whose activity depended on social rank: 535 genes that were more highly expressed in high-ranking individuals and 452 genes with higher activity in low-ranking individuals. Many of these genes were involved with the immune system; in particular, genes involved in inflammation were more active in low-ranking individuals. Further testing revealed that low-ranking monkeys also had fewer cytotoxic T-cells, a kind of white blood cell that attacks infected and cancerous cells. Earlier research suggests that the stress of a low social rank compromises the immune system—which fits with the finding about T-cells—but may also trigger the immune system to respond when it does not need to, which fits with the finding about inflammation. Findings about the relationship between stress, social status and the immune system are not clear cut, however; for example, some studies have found that having a higher rank is more stressful than having a lower rank. © 2012 Scientific American

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 13: Memory, Learning, and Development
Link ID: 16632 - Posted: 04.10.2012

by Sarah C. P. Williams Ten minutes after they play in a competitive soccer match with an audience of friends and family cheering them on, men from the Tsimane people in lowland Bolivia have testosterone levels 30% higher than they were before the game. If the players were athletes in the United States, this number wouldn't be surprising. But Tsimane men have much lower levels of testosterone throughout their lives than do men in developed countries. The findings may provide clues to how the body regulates short-term versus long-term increases in the hormone. The Tsimane, a population of 15,000 spread among small villages in the Amazon, rely on farming, hunting, and gathering to survive. With only recent exposure to immunizations and modern sanitation methods, the people are plagued by infections, pathogens, respiratory illnesses, and gastrointestinal diseases. This disease burden suggested to anthropologist Benjamin Trumble of the University of Washington, Seattle, that the men would likely have low testosterone levels. "Testosterone is quite energetically expensive and is also thought to interfere with immune functioning," he notes. "So if you're part of a population that faces lots of parasites and pathogens, generally you've adapted to have less testosterone." To confirm his hypothesis, Trumble and colleagues recruited 88 Tsimane men who were playing in a competitive inter-village soccer tournament. Despite their hunter-gatherer lifestyle, the Tsimane have had increasing contact with other populations over the past few decades and have become avid fans of soccer. Men who were participating in the tournament play, on average, three times a week. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 16585 - Posted: 03.29.2012

By Victoria Gill Science reporter, BBC Nature Japanese honeybees' response to a hive-invading giant hornet is efficient and dramatic; they form a "bee ball" around it, serving to cook and asphyxiate it. Now, researchers in Japan have measured the brain activity of honeybees when they form this killer ball. One highly active area of the bees' brains, they believe, allows them to generate the constant heat which is deadly for the hornet. The team published their findings in the open-access journal, PLoS One. Prof Takeo Kubo from the University of Tokyo explained that "higher centres" of the bee's brain, known as the mushroom bodies, were more active in the brains of Japanese honeybees when they were a part of the "hot defensive bee ball". To find this out, the team lured the bees to form their ball by attaching a hornet to the end of a wire and inserting the predator into the hive. This simulated invasion caused the bees to swarm around the hornet. The researchers then plucked a few of the bees from the ball and measured, throughout each of their tiny brains, the relative amount of a chemical that is known to be a "marker" of brain activity. "We found that similar [brain] activity is evoked when the Japanese honeybees are simply exposed to high temperature (46C) in the laboratory," the researcher told BBC Nature. BBC © 2012

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 16526 - Posted: 03.17.2012

By Rebecca Cheung When it comes to male crayfish, not all claws are created equal. In these crustaceans, the left and right claws might be very different sizes — and the larger one isn’t necessarily stronger, researchers report online March 14 in Biology Letters. This deceptiveness could help crayfish bluff or trick an opponent during a fight, says study coauthor Robbie Wilson, a biologist at the University of Queensland in Brisbane, Australia. What’s more, the findings suggest that within a species, “dishonesty occurs in nature more commonly than we expect,” Wilson says. During a clash, a male crayfish sizes up his opponent when deciding whether to fight or flee. Previously, scientists found that stronger, smaller-clawed crayfish would back down from weaker, larger-clawed opponents. So, it was clear that some bluffing occurred between these crustaceans. In this new work, Wilson and his colleague Michael Angilletta Jr., of Arizona State University in Tempe, compared claw size and strength in the slender male crayfish, Cherax dispar, a species native to Queensland. By having crayfish squeeze down on instruments that resembled tweezers, researchers could measure the force exerted by individual claws. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 14: Attention and Consciousness
Link ID: 16517 - Posted: 03.15.2012

Europe's top human rights watchdog, the Council of Europe, has urged Germany to end the practice of surgically castrating sex offenders. The council's anti-torture committee said such voluntary treatment, albeit rare in Germany, was "degrading". In Germany no more than five sex offenders a year have been opting for castration, hoping it will lower their sex drives and reduce their jail term. The committee's recommendations are not binding but have great influence. The committee's official title is the European Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment (CPT). "Surgical castration is a mutilating, irreversible intervention and cannot be considered as a medical necessity in the context of the treatment of sexual offenders", the CPT report said. It was based on an investigation in Germany carried out in November-December 2010. The BBC's Stephen Evans in Berlin says the German authorities argue that castration is not a punishment but a treatment which enables, as a government statement put it, "suffering tied to an abnormal sex drive… to be cured, or at least alleviated". Research for the report revealed that of the 104 people operated on between 1970 and 1980, only 3% reoffended, compared with nearly half of those who refused castration or were denied it by the authorities. BBC © 2012

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 16425 - Posted: 02.25.2012

By DOUGLAS QUENQUA Tropical fish hobbyists will tell you their tanks are a source of relaxation, but recent research suggests the fish might disagree. Nearly 13 million American households contain a fish tank, and the average tank size is less than 10 gallons. Yet a study comparing the behavior of common freshwater fish in a variety of habitats found that those kept in such small tanks were considerably more aggressive than those in larger ones — more likely to fight, flare their gills and guard whatever tiny alcoves they could find. “In larger tanks, the fish were not in continuous eyesight of each other, and were swimming around checking everything out rather than beating the heck out of each other,” said the study’s author, Ronald G. Oldfield, a professor of biology at Case Western Reserve University. The fish in question were Midas, or “red devil” cichlids, a species popular among hobbyists for their brilliant colors and active swimming habits. Dr. Oldfield used only very young fish to eliminate aggressive behaviors associated with mating. Dr. Oldfield concedes that the emotional well-being of fish may not tug many heartstrings. “It’s probably not the end of the world,” he said in a telephone interview. Even the Humane Society, which routinely has commercials featuring slow-motion video of abused pets, does not offer guidelines for the treatment of pet fish. © 2011 The New York Times Company

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 16192 - Posted: 12.27.2011