Links for Keyword: Aggression

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By CHARLES SIEBERT ‘We’re not going anywhere,” my driver, Nelson Okello, whispered to me one morning this past June, the two of us sitting in the front seat of a jeep just after dawn in Queen Elizabeth National Park in southwestern Uganda. We’d originally stopped to observe what appeared to be a lone bull elephant grazing in a patch of tall savanna grasses off to our left. More than one “rogue” crossed our path that morning — a young male elephant that has made an overly strong power play against the dominant male of his herd and been banished, sometimes permanently. This elephant, however, soon proved to be not a rogue but part of a cast of at least 30. The ground vibrations registered just before the emergence of the herd from the surrounding trees and brush. We sat there watching the elephants cross the road before us, seeming, for all their heft, so light on their feet, soundlessly plying the wind-swept savanna grasses like land whales adrift above the floor of an ancient, waterless sea. Then, from behind a thicket of acacia trees directly off our front left bumper, a huge female emerged — “the matriarch,” Okello said softly. There was a small calf beneath her, freely foraging and knocking about within the secure cribbing of four massive legs. Acacia leaves are an elephant’s favorite food, and as the calf set to work on some low branches, the matriarch stood guard, her vast back flank blocking the road, the rest of the herd milling about in the brush a short distance away. Copyright 2006 The New York Times Company

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 9449 - Posted: 06.24.2010

In the Minds of Men

Whether war or violent crime touches our lives directly, or whether we are subjected to it secondhand through the media, on some level we experience the connection between our own biology and our emotions each day. Anyone who’s been cut off in traffic, even once, has felt the connection between that first perceived insult and the flush of anger, the spike of adrenaline, the body’s fight-or-flight mechanisms that seem built into human nature. Aggressiveness of character, early nineteenth-century phrenologists believed, could be judged by observing bumps on the skull; modern scientists peer into the brain beneath the bone. The idea that violence just might be hardwired into our genes has grown ever more acceptable as the technology, including gene mapping and brain scans, has grown more sophisticated. By the mid-1980s, according to one study, about forty percent of students believed war was intrinsic to human nature. Moreover, Wesleyan University psychology professor David Adams found that these students became less likely to engage in activities for peace. To challenge the alleged biological findings being used to justify violence and war, he convened a group of scientists at the Sixth International Colloquium on Brain and Aggression held in May 1986, and together, twenty of them drafted the Seville Statement on Violence. It concluded that, “Just as ‘wars begin in the minds of men,’ peace also begins in our minds. The same species who invented war is capable of inventing peace. The responsibility lies with each of us.” The statement was endorsed by the 65,000-member American Psychological Association at a 1987 meeting in New York, but of 400 invited reporters, only four—from the APA Monitor, Tass, ADN from then-East Germany, and the People’s Daily World of the U.S. Communist Party—showed up to cover the event. © 2002 Science & Spirit Magazine.

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 7065 - Posted: 06.24.2010

Monkeys' art of war has lessons for human conflict

by Jim Giles Studying animal conflicts could help shed light on human wars – that is the hope from a study of the choices that monkeys make when deciding to fight or remain at peace. Competition for resources is often assumed to be a main cause of conflict in both humans and other animals, says Jessica Flack at the Santa Fe Institute in New Mexico, but that might be wrong. "We find that fighting is based on memories of what other individuals did last." Flack and colleagues Simon DeDeo and David Krakauer analysed data from 160 days of field observations of a group of 84 pigtailed macaques at the Yerkes National Primate Research Center in Lawrenceville, Georgia. The team paid particular attention to which animals fought and how long each fight lasted. Instead of explaining the monkey's fighting ways by dreaming up a strategy based, for example, on the reward value of winning a fight for food or a mate, Flack and colleagues decided to look for strategies suggested by the data alone. They made no assumption about the reasons for the monkeys' behaviour and looked only at patterns of behaviour leading up to fights. This allowed them to determine the relative importance of the factors that led up to a fight. They found that the strategy that best explained involvement in a fight was one in which decisions were based on the presence or absence of pairs of other monkeys. This suggests that social dynamics play a central role. © Copyright Reed Business Information Ltd.

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 14071 - Posted: 06.24.2010

Why alpha-male baboons allow subordinates sex treats

by Bob Holmes Sometimes it pays to give underlings a treat. Dominant male chacma baboons allow lower-ranking males to mate with their females as a way to protect the dominant male's own offspring in their absence. That's the conclusion reached by Louise Barrett of the University of Lethbridge in Alberta, Canada, who studied 11 years of observations from a baboon troop in De Hoop Nature Reserve, South Africa. Chacma baboons have a despotic social structure in which a single alpha male can almost completely monopolise mating opportunities by guarding females during their oestrus periods. Yet Barrett found that subordinate males in the De Hoop troop fathered 23 of 64 offspring during that time. Closer analysis showed that this was not because the alpha male was too tired, too busy, or too inexperienced to guard the females. Instead, he appeared to be willingly ceding copulations to subordinate males Spare dads The alpha male's apparent generosity may be a strategy for protecting his young after he is no longer around. When an alpha male dies or wanders off, new alpha males – usually from an outside group – move in, and tend to try to kill infants from the previous regime. Having "spare dads" in the troop may help ensure that these infants receive protection, says Barrett. © Copyright Reed Business Information Ltd

Related chapters from BP6e: 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: 13659 - Posted: 06.24.2010

Gamers are more aggressive to strangers

by Ewen Callaway Victorious gamers enjoy a surge of testosterone – but only if their vanquished foe is a stranger. When male gamers beat friends in a shoot-em-up video game, levels of the potent sex hormone plummeted. This suggests that multiplayer video games tap into the same mechanisms as warfare, where testosterone's effect on aggression is advantageous. Against a group of strangers – be it an opposing football team or an opposing army – there is little reason to hold back, so testosterone's effects on aggression offer an advantage. "In a serious out-group competition you can kill all your rivals and you're better for it," says David Geary, an evolutionary psychologist at the University of Missouri in Columbia, who led the study. However, when competing against friends or relatives to establish social hierarchy, annihilation doesn't make sense. "You can't alienate your in-group partners, because you need them," he says. It's his hormones Measuring these effects, however, hasn't been easy. Victors in sporting events are known to experience a burst in testosterone – particularly if they contributed to the win. But physical exertion also boosts testosterone, so it is hard to be sure just what causes an athlete's hormonal surge. © Copyright Reed Business Information Ltd

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 13312 - Posted: 06.24.2010

War, what is it good for? It made us less selfish

By Steve Connor, Science Editor One of the defining characteristics of being human is the supreme act of personal sacrifice needed to lay down one's life for the good of the group – but could such altruism be hard-wired in our genes as a result of Darwinian evolution? Biologists have argued for decades about the evolution of altruism and long ago came to the conclusion that Darwinian natural selection cannot explain acts of supreme personal sacrifice except those directly connected with helping the survival of close blood relatives who share similar genes. But now a study has suggested that altruism in prehistoric human societies may after all have resulted from a form of natural selection caused by a state of near-continual warfare between competing tribes of hunter gatherers, an idea that Charles Darwin himself first suggested in his 1873 book The Descent of Man. A scientist has suggested that because so many of the 200,000 years of human history were spent during our hunter-gatherer phase, before the invention of agriculture, less than 10,000 years ago, this long period in our evolutionary history shaped our social behaviour. Moreover, he believes that altruism may have evolved directly as a result of tribal warfare because personal sacrifice was the key that enabled one group to be victorious over another. Samuel Bowles, of the Santa Fe Institute in New Mexico, said: "Warfare was sufficiently common and lethal among our ancestors to favour the evolution of what I call parochial altruism, a predisposition to be co-operative towards group members and hostile towards outsiders. ©independent.co.uk

Related chapters from BP6e: 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: 12922 - Posted: 06.24.2010

Grooming your way to the top

Matt Kaplan Among most mammals, being the biggest and meanest is the only way to become the alpha male with a choice of mates. But in chimpanzee society, it seems that being nice can be just as powerful. Grooming among chimpanzees has been proposed by some primatologists to be a strategy for solidifying relationships within groups1. Yet in spite of the many studies exploring this, no one had determined whether chimpanzees use grooming as a tactic for obtaining alpha status. Indeed, the conventional view, based largely on anecdotal evidence, is that bigger and tougher is better. Researchers at the University of Minnesota's Jane Goodall Institute Center for Primate Studies have now collated ten years of behavioural data on three male chimpanzee in Gombe National Park, Tanzania. Chimpanzees within the park have been routinely weighed by park staff2, allowing Mark Foster and his team from the institute to work out which tactics chimpanzees of dramatically different sizes used both before and after they became alpha males. Carrying 51.2 kilograms at his peak, Frodo, the second-largest male ever weighed at Gombe, proved to be the quintessential bully. With consistent high rates of aggression, including attacks on the researchers, he was alpha male from 1997-2003. But one of Gombe's smallest males, a 37-kilogram chimpanzee named Wilkie, followed a different path. Foster and his team noticed that Wilkie was an obsessive groomer, attending to others far more often than his rivals did. He also spent most of his time grooming his female partners, unlike most alpha males who only receive grooming from their partners. Yet, in spite of his lesser size and gentler nature, Wilkie held alpha status from 1989–92. © 2009 Nature Publishing Group

Bad boys can blame behaviour on their hormones

Andy Coghlan Out-of-control boys facing spells in detention or anti-social behaviour orders can now blame it all on their hormones. The "stress hormone" cortisol – or low levels of it – may be responsible for male aggressive antisocial behaviour, according to new research. The work suggests that the hormone may restrain aggression in stressful situations. Researchers found that levels of cortisol fell when delinquent boys played a stressful video game, the opposite of what was seen in control volunteers playing the same game. The results suggest that biology rather than peer pressure might play a larger role than previously thought in delinquent behaviour, and raise new possibilities for diagnosing and treating such disorders. Virtual rival The study pitted each volunteer against a pugnacious, virtually generated rival boy in a computer game that had them competing for a monetary reward. The game was deliberately rigged to subject volunteers to stress, frustration, provocation, and taunting from their adversary. Saliva samples from the 95 control volunteers showed that their cortisol levels rose by an average of 48%, as expected in stressful situations. But in the 70 participants with conduct disorder, levels of cortisol dropped by an average of 30%. © Copyright Reed Business Information Ltd

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 12089 - Posted: 06.24.2010

How does day length affect aggression in mice? It's in the genes

COLUMBUS, Ohio – Imagine if a naturally occurring chemical in your body could help make you feel more calm and relaxed – but it would only work during the long days of summer. The same chemical would, instead, make you aggressive and nasty when you were exposed to less daylight during the winter. That's exactly what occurs for a specific species of mouse, according to a new study at Ohio State University, published online this week in the Proceedings of the National Academy of Sciences. Researchers found that the class of hormones called estrogens acts to increase aggression in the Oldfield Mouse (Peromyscus polionotus) during the short days of winter. However, when daylight increases in the summer, estrogen decreases aggression among male Oldfield mice, a species commonly found in the southeastern United States. The finding is significant because it is one of the first studies to show how a very simple environmental factor – in this case, the length of daylight – can have a powerful effect on how genes influence behavior, at least in some species. "We found that estrogen has totally opposite effects on behavior in these mice depending only on how much light they got each day," said Brian Trainor, co-author of the study and postdoctoral fellow in psychology and neuroscience at Ohio State University.

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 10: Biological Rhythms and Sleep
Link ID: 10325 - Posted: 06.24.2010

Rivalry leaves its mark on primate brains

Roxanne Khamsi Brain structures in primates have developed due to different pressures on males and females to keep up with social or competitive demands, a new study suggests. A comparison of brains from 21 primate species, including gorillas and chimps, suggests that those with greater male-on-male competition have more brain matter devoted to aggression and coordination. Whereas those species in which there is more social mixing between males and females have evolved bigger brains with higher-level thinking. Competition for status and mates among primates might have influenced brain evolution, the researchers say. They add that contrasting brain types resulting from behavioural differences between the sexes might be a factor in other branches of mammalian brain evolution beyond anthropoid primates. In the early 1980s, a group of researchers published information about the brain anatomy of 21 different primate species – which included gorillas, chimps and rhesus monkeys, but not humans. The team took each brain and cut it into thin slices. They photographed each slice and marked the boundaries of the brain structures they saw. By measuring the areas of these marked regions, the scientists were able to reconstruct various brain structures and estimate their volume. © Copyright Reed Business Information Ltd

Spear-wielding chimps snack on skewered bushbabies

Rowan Hooper In a revelation that destroys yet another cherished notion of human uniqueness, wild chimpanzees have been seen living in caves and hunting bushbabies with spears. It is the first time an animal has been seen using a tool to hunt a vertebrate. Many chimpanzees trim twigs to use for ant-dipping and termite-fishing. But a population of savannah chimps (Pan troglodytes verus) living in the Fongoli area of south-east Senegal have been seen making spears from strong sticks that they sharpen with their teeth. The average spear length is 63 centimetres (25 inches), says Jill Pruetz at Iowa State University in Ames, US, who observed the behaviour. And the method of procuring food with these tools is not simply extractive, as it is when harvesting insects. It is far more aggressive. They use the spears to hunt one of the cutest primates in Africa: bushbabies (Galago senegalensis). Bushbabies are nocturnal and curl up in hollows in trees during the day. If disturbed during their slumbers – if their nest cavity is broken open, for example – they rapidly scamper away. It appears that the chimps have learnt a grisly method of slowing them down. Chimps were observed thrusting their spears into hollow trunks and branches with enough force to injure anything inside the holes, Pruetz’s research team says. The chimps used a “power grip” and made multiple downward stabs – much the same way as a human might wield a dagger. © Copyright Reed Business Information Ltd.

Fighting like a girl or boy determined by gene in fruit flies

Boston, MA -- Fighting like a girl or fighting like a boy is hardwired into fruit fly neurons, according to a study in the Nov. 19 Nature Neuroscience advance online publication by a research team from Harvard Medical School and the Institute of Molecular Pathology in Vienna. The results confirm that a gene known as "fruitless" is a key factor underlying sexual differences in behavior. The findings mark a milestone in an unlikely new animal model for understanding the biology of aggression and how the nervous system gives rise to different behaviors. "Aggression is a very serious problem in society, and it's a problem with a biological and genetic component," said co-author Edward Kravitz, the George Packer Berry professor of neurobiology at HMS, who developed the fruit fly fighting model used. "We want to understand that. I can't think of a better system to study than fruit flies. And no one gets hurt." The fruitless gene is known for its role in male courtship. The large gene makes a set of male-specific proteins found exclusively in the nervous system of fruit flies, in about 2 percent of neurons. The proteins are necessary for normal courting. Males missing the proteins do not court females, and they sometimes court males, other research groups have shown. Females with a male version of the gene perform the male courting ritual with other females. The same gene directs another sex-specific behavior – fighting patterns, the new study shows. Female fighting, for example, largely involves head butts and some shoving. Males prefer lunges; they rear up on their back legs and snap their forelegs down hard – sometimes nailing an opponent that is slow to retreat.

CHANGING LENGTH OF DAYS REVERSES HOW ESTROGEN AFFECTS AGGRESSIVENESS IN MICE

COLUMBUS , Ohio – New research shows how simply varying the length of daylight to which mice are exposed to can change how aggressively they react to other mice. The study found that in the short days of winter, the class of hormones called estrogens acts to increase aggression in males of a particular type of mouse called the Oldfield Mouse (Peromyscus polionotus). However, in the long days of summer, estrogen decreases aggression among male Oldfield mice, a species commonly found in the southeastern United States . “We found that estrogen has totally opposite effects on behavior in these mice depending only on how much light they got each day,” said Brian Trainor, co-author of the study and postdoctoral fellow in psychology and neuroscience at Ohio State University. “It is quite a surprising finding.” The study is also important because it is one of the few that has shown how hormones other than testosterone can affect aggression in mammals. “This goes against the common belief that testosterone is the hormone that regulates aggression,” said Randy Nelson, co-author and professor of psychology and neuroscience at Ohio State. “There are now several studies showing that in some species estrogen plays a key role in aggressiveness as well.”

Fruit Fly Aggression Studies Have Relevance to Animal, Human Populations

Even the tiny, mild-mannered fruit fly can be a little mean sometimes – especially when there’s a choice bit of rotten fruit to fight over. And, like people, some flies have shorter tempers than others. Researchers in the North Carolina Sate University genetics department have identified a suite of genes that affect aggression in the fruit fly Drosophila melanogaster, pointing to new mechanisms that could contribute to abnormal aggression in humans and other animals. The study, led by doctoral student Alexis Edwards in the laboratory of Dr. Trudy Mackay, William Neal Reynolds Professor of Genetics, appears online in PloS Genetics. Feisty flies themselves may not be very scary, but their genes and biochemistry have more in common with those of humans than the casual observer might suspect, and geneticists can subject flies to experiments that simply can’t be done on higher organisms. To measure aggression, the researchers starved male flies for an hour and a half, then gave them a small food droplet and watched them duke it out, counting the number of times a focal fly would chase, kick, box, or flick his wings at other flies.

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 9373 - Posted: 06.24.2010

A version of a gene previously linked to impulsive violence appears to weaken brain circuits that regulate impulses, emotional memory and thinking in humans, researchers at the National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) have found. Brain scans revealed that people with this version – especially males – tended to have relatively smaller emotion-related brain structures, a hyperactive alarm center and under-active impulse control circuitry. The study identifies neural mechanisms by which this gene likely contributes to risk for violent and impulsive behavior through effects on the developing brain. NIMH intramural researchers Andreas Meyer-Lindenberg, M.D., Daniel Weinberger, M.D., Ph.D., and colleagues report on their magnetic resonance imaging (MRI) study online in the Proceedings of the National Academy of Sciences during the week of March 20, 2006. "These new findings illustrate the breathtaking power of 'imaging genomics' to study the brain's workings in a way that helps us to understand the circuitry underlying diversity in human temperament," said NIH Director Elias A. Zerhouni, M.D., who conducted MRI studies earlier in his career. "By itself, this gene is likely to contribute only a small amount of risk in interaction with other genetic and psychosocial influences; it won't make people violent," explained Meyer-Lindenberg. "But by studying its effects in a large sample of normal people, we were able to see how this gene variant biases the brain toward impulsive, aggressive behavior."

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress; Chapter 4: The Chemical Bases of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 8671 - Posted: 06.24.2010

Animal models show that anabolic steroids flip the adolescent brain's switch for aggression

Anabolic steroids not only make teens more aggressive, but may keep them that way into young adulthood. The effect ultimately wears off but there may be other, lasting consequences for the developing brain. These findings, published in February's Behavioral Neuroscience, also showed that aggression rose and fell in synch with neurotransmitter levels in the brain's aggression control region. Behavioral Neuroscience is published by the American Psychological Association (APA). Neuroscientists are deeply concerned about rising adolescent abuse of anabolic-androgenic steroids (AASs), given the National Institute on Drug Abuse's estimate that nearly half a million eighth- and 10th-grade students abuse AASs each year. Not only do steroids set kids up for heavier use of steroids and other drugs later in life, but long-term users can suffer from mood swings, hallucinations and paranoia; liver damage; high blood pressure; as well as increased risk of heart disease, stroke and some types of cancer. Withdrawal often brings depression, and recent research suggests that some AASs may even be habit-forming. Overseen by Richard Melloni Jr., PhD, of Northeastern University in Boston, the current study of 76 adolescent hamsters compared how individual hamsters behaved when another hamster was put into their cages. Normally mild-mannered hamsters still defend their turf, learning aggression during puberty by play-fighting, much like humans. Their roughhousing normally includes wrestling and nibbling – pretty tame stuff.

Violent video games lead to brain activity characteristic of aggression

EAST LANSING, Mich. – A Michigan State University researcher and his colleagues have shown that playing violent video games leads to brain activity pattern that may be characteristic for aggressive thoughts. In a functional magnetic resonance imaging (fMRI) study, 13 male research participants were observed playing a latest-generation violent video game. Each participant’s game play was recorded and content analyzed on a frame-by-frame basis. “There is a causal link between playing the first-person shooting game in our experiment and brain-activity pattern that are considered as characteristic for aggressive cognitions and affects,” said Ren� Weber, assistant professor of communication and telecommunication at MSU and a researcher on the project. “There is a neurological link and there is a short-term causal relationship. “Violent video games frequently have been criticized for enhancing aggressive reactions such as aggressive cognitions, aggressive affects or aggressive behavior. On a neurobiological level we have shown the link exists.” Weber conducted the research with his colleagues Klaus Mathiak of RWTH Aachen University (Germany) and Ute Ritterfeld of the University of Southern California. © 2005 Michigan State University Division of University Relations

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 8026 - Posted: 06.24.2010

Oxytocin raises aggression, cuts anxiety during lactation; similar effects on virgin rats

STEAMBOAT SPRINGS, Colorado – Maternal aggressive/protective behavior is recognized throughout mammalian species, especially during lactation. When hiking, we warn our kids not to approach bear cubs, or to get between a cub and the mother. While driving and you see a fawn, you know a doe can't be too far away and will run headlong to protect it. The same neurohypophyseal (NH) hormone, oxytocin (OT), is responsible for both the physiological and behavioral changes, but the site of action is quite different. OT is released during parturition and in lactation not only from NH terminals into the bloodstream in order to support reproductive systems, but also within the brain, into the supraoptic nucleus (SON) and paraventricular nucleus (PVN), where it has marked behavioral impact. OT release in the brain is involved with such reproductive events as "morphological plasticity, autoregulation of OT neuronal activity and promotion of maternal behavior, including maternal aggressive behavior to protect offspring," Inga D. Neumann of the University of Regensburg, Germany, notes. "Thus in lactating rats from a line bred for high-anxiety behavior, or HAB, OT release within both the central amygdala and the PVN was positively correlated with the level of maternal offensive behavior against an intruder." In addition, the lactating HAB dams display higher aggression and central OT release compared with a low-anxiety line.

STEROID USE CAUSES LONG-TERM AGRESSION, NU REPORT INDICATES

NIH-funded research delves into long term effects of anabolic steroid use BOSTON, Mass. – With the recent revelations about steroid use in Major League Baseball and the bust last week of several Oakland Raiders players for drug abuse, Northeastern University psychology professor Richard Melloni , who studies the link between steroid use and aggression, has recently found evidence that use of anabolic steroids may have long-term effects on players’ behavior and aggression levels well after they stop abusing these performance enhancing drugs. With funding from the NIH (recently extended through 2008), Melloni and doctoral student Jill Grimes have been studying how steroids used during adolescence may permanently alter the brain's ability to produce serotonin. In their experiments, adolescent Syrian hamsters - given their similar brain circuitry to human adolescents – were administered doses of anabolic steroids and then measured for aggressiveness over certain periods of time. The researchers initially hypothesized that steroid use during adolescence might permanently alter the brain's chemistry and a person's tendency toward aggression long after use has stopped. Their most recent findings, published this week in Hormones and Behavior , enabled them to confirm this hypothesis and conclude that there is indeed a lengthy price – namely long-term aggression – to pay for drug abuse even after the ingestion of steroids ceases.

Wild Young Brains

Are violence and aggression genetic or a response to our upbringing? As this ScienCentral news video reports, psychologists say it's both–but parenting can shape the effects of childrens' genes. Nurture just might trump nature when it comes to certain aspects of behavioral development. Psychologists who studied rhesus monkeys, which share over 92 percent of their genetic material with us, found that mothers not only took care of their young but also corrected any bad behavior. "Mothers are very good at giving the kind of inputs that change behavior," says J. Dee Higley, a research psychologist at the National Institute of Alcohol Abuse and Alcoholism , "but that's happening at the very time that the brain is changing, when it needs that kind of input. It's almost as if evolution said, 'let's put mothers there so that the brain gets the right kind of input.'" © ScienCentral, 2000-2003.

Related chapters from BP6e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 4514 - Posted: 06.24.2010

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