Why men are more aggressive: What a mother should know

June 21, 2006

Aggression in men may be due to variations in one of two genes involved in the activity of the neurotransmitter serotonin, according to results of a study reported at the 6th International Congress of Neuroendocrinology (ICN 2006), which takes place June 19 — 22 at the David L. Lawrence Convention Center in downtown Pittsburgh.

However, men with the "aggression" genes aren't necessarily all cads; genetics appears to be predictive only if men have hostile attitudes and fathers who never completed high school. Moreover, a genetic predisposition toward aggression could be rebuffed by a mother who nurtures her infant, suggests another study involving primates.

Summaries of these studies' findings and research revealing new information about the molecular and biophysical mechanisms that determine sexual arousal and sexual behavior follow:

No argument here: Research determining why some men are more aggressive
What pushes some men to the outer limits of machismo, to be more confrontational or apt to get into scuffles and arguments? According to results of a study involving 531 white men of European descent, belligerence may be attributable to variations in one of two genes involved in the activity of the neurotransmitter serotonin. However, men with the "aggression" genes aren't necessarily all cads, cautions Stephen Manuck, Ph.D., professor of psychology at the University of Pittsburgh, who led the research. Genetics appears to be predictive of aggression only if men also have more cynical and hostile attitudes toward others or fathers who never completed high school.

The Pitt study is the first to look at whether aggression in "normal" men may, in part, be attributed to the same serotonin-related genetic alterations that have been associated with aggressive behaviors in certain psychiatric and criminal populations. Indeed, the study found those who reported past fights, conflicts with authority figures or breaking objects in bouts of anger were more likely to carry the "low activity" MAOA gene variant that's been linked to criminal violence. Monoamine oxidase-A, or MAOA, is an enzyme that inactivates serotonin, helping to keep its levels in proper balance. Yet the low activity MAOA gene was only associated with aggressive "acting out" among men with oppositional attitudes. Variation in another serotonin gene, the serotonin 2A receptor, which is necessary for the neurotransmitter to act, also was predictive of antagonistic behavior, but only among men whose fathers had less than a high-school education. The same gene has been implicated in personality and anti-social disorders and in some criminal offenders.

Maternal buffer can prevent aggression
It can be a real jungle out there, and parents often do their best to shield their children from the worst of influences. According to new research, mothers can offer some added protection that fathers can't: a buffer against the development of aggressive behavior. According to primate studies, those with a genetic susceptibility for hostile behavior can grow up to be docile in nature, provided they had loving and caring mothers as infants.

Up to 10 percent of rhesus monkeys living in the wild are overly aggressive and react inappropriately even in the most benign situations, a trait they typically develop at a young age and seldom grow out of. Moreover, researchers have recently found, these aggressive animals have lower levels of the brain chemical serotonin, an observation noted through adulthood. Like their wild counterparts, monkeys studied in the laboratory that have a variation of a certain serotonin-related gene also make less serotonin and are more impulsive and aggressive, but only if they had mothers who did not bond with them as infants. As Stephen J. Suomi, Ph.D., chief, Laboratory of Comparative Ethology at the National Institute of Child Health & Human Development, has demonstrated, monkeys with the same gene-based serotonin deficiency who were reared by more nurturing mothers avoid developing aggressive behaviors. "Maternal buffering," he suggests, can trump genetics. The same may be true in humans.

Getting to the essential mechanisms of brain arousal and sexual behavior
To understand what brings about arousal of the central nervous system leading to sexual behavior, scientists have had to discover specific biochemical reactions within a select group of neurons in the hypothalamus, says Donald Pfaff, Ph.D., professor and head of the Laboratory of Neurobiology and Behavior at Rockefeller University. The process involves a complement of sex steroid hormones, perhaps as many as 120 genes and a host of environmental variables (not least among them, arousing stimuli and a suitable mate).

In these brain mechanisms, interactions between genes and the immediate environment play an essential part. Other, longer-term interactions stem from an animal's treatment about the time of birth. Those longer-term interactions are hypothesized to depend on chemical modification of either DNA through a process called methylation or of proteins covering the DNA. These so-called epigenetic mechanisms can produce heritable changes in behaviors without changing the animal's DNA sequence. Dr. Pfaff's new results reveal some of the molecular and biophysical mechanisms that dictate when and how chemical messages for generalized arousal affect the neurons in the hypothalamus that control sexual arousal and sexual behaviors.

Held in a different part of the world every four years under the auspices of the International Neuroendocrine Federation, this year's congress — Bridging Neuroscience and Endocrinology — is being sponsored by the American Neuroendocrine Society and the University of Pittsburgh School of Medicine. The first full day of the program, June 20, is being held in conjunction with the 10th Annual Meeting of the Society for Behavioral Neuroendocrinology.

University of Pittsburgh Medical Center

On Aggression (Harvest Book, Hb 291)
by Konrad Lorenz (Author)

This work has had significant impact on the social and biological sciences and is now a classic point of reference for investigations of behavioral patterns. Lorenz presents his findings on the mechanism of aggression and how animals control destructive drives in the interest of the species. Translated by Marjorie Kerr Wilson. A Helen and Kurt Wolff Book

Aggression, Antisocial Behavior, and Violence among Girls: A Developmental Perspective (The Duke Series in Child Develpment and Public Policy)
by Martha Putallaz PhD (Editor), Karen L. Bierman Phd (Editor)

From leading authorities, this book traces the development of female aggression and violence from early childhood through adulthood. Cutting-edge theoretical perspectives are interwoven with longitudinal data that elucidate the trajectories of aggressive girls' relationships with peers, with later romantic partners, and with their own children. Key issues addressed include the predictors of social and physical aggression at different points in the lifespan, connections between being a victim and a perpetrator, and the interplay of biological and sociocultural processes in shaping aggression in girls. Concluding commentaries address intervention, prevention, juvenile justice, and related research and policy initiatives.

Human Aggression and Violence: Causes, Manifestations, and Consequences (The Herzliya Series on Personality and Social Psychology)
by Phillip R. Shaver (Editor), Mario Mikulincer (Editor)

Violence and aggression have existed as long as mankind, and the need to understand and control these forces has only continued to grow throughout history. Thanks to the advance of psychological research within the social and behavioral sciences, as well as several other scientific disciplines, we have more knowledge than ever before about the genetic, developmental, interpersonal, and cultural causes of aggression. Yet these findings have not been integrated into meaningful discussions about how to transform aggression research into practical applications. With so many answers to the question "What makes a person violent?" there is surprisingly little insight into "How do we prevent violence?"

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The Cambridge Handbook of Violent Behavior and Aggression (Cambridge Handbooks in Psychology)
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Violence is a complex behavior that manifests itself every day in acts of terrorism, through exposure in the media, and in our families and neighborhoods. Understanding the origins of violent behavior and aggression, its developmental course, and its impact on individuals and societies will allow us to develop appropriate preventative interventions and policies that will affect us in our everyday lives. This handbook is unique in its depth of coverage of violence and aggressive behavior, its multidisciplinary focus, and its presentation of cutting-edge research by the leading authors in the field.

Biology of Aggression
by Randy J. Nelson (Editor)

Unchecked aggression and violence take a significant toll on society. Even if we manage to avoid being the direct victim of a violent act, the effects of aggression and violence reach us all: We hear about the mauling of a woman by an aggressive dog, our children are bullied at school, or we deal with impulsive violence while commuting to work or attending a sporting event. Reflecting psychology in general, the dominant roles of learning and environmental influences - both social and nonsocial - have traditionally been prominent in discussions of the etiology of human aggression. Biological factors have not been considered sufficiently important to investigate in the search for ways of dealing with human aggression or violence. With recent advances in pharmacology and genetic...

Behavior Adjustment Training: Bat for Fear, Frustration, and Aggression in Dogs
by Grisha Srewart (Author)

Think functional to solve your dog s reactivity issues

Behavior Adjustment Training (BAT) was developed by author Grisha Stewart to rehabilitate and prevent dog reactivity. BAT looks at the function of growling, lunging, or fleeing and helps dogs learn socially acceptable behaviors that serve that same function. In a nutshell, BAT builds confidence by giving dogs a chance to learn to control their environment through peaceful means. That makes BAT very empowering to your dog or puppy, in a good way. It s also empowering for you, as you learn how to understand your dog and help him learn to safely get along with people, dogs, and other triggers.

You will learn:

How to encourage or shape a replacement behavior that provides your dog the same functional reward as...

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This down-to-earth manual will teach you how to use behavior modification to retrain a dog that bullies other dogs, or becomes fearful when approached by other dogs. From the award winning author of The Culture Clash and Mine! A Practical Guide to Resource Guarding in Dogs.
Includes descriptions of:
Common types of aggression
Assessing prognosis
Remedial socialization
On-leash manners training
Proximity sensitivity
Play style and skills
Resource guarding
Prevention

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Aggression Replacement Training: A Comprehensive Intervention for Aggressive Youth, Third Edition (Revised and Expanded)(CD included)
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The book provides a coordinated, three-part training approach: Prosocial Skills, Anger Control and Moral Reasoning for grades 6 to 12.
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Living with the Passive-Aggressive Man: Coping with Hidden Aggression - From the Bedroom to the Boardroom
by Scott Wetzler (Author)

DO YOU KNOW ONE OF THESE MEN? The catch-me-if-you-can lover... Phil's romantic and passionate one minute, distant and cold the next. The deviously manipulative coworker or boss... Jack denies resenting Nora's rapid rise in the company, but when they're assigned to work together on a project, he undermines her. The obstructionist, procrastinating husband... Bob keeps telling his wife he'll finish the painting job he began years ago, but he never seems to get around to it. These are all classic examples of the passive-aggressive man. This personality syndrome -- in which hostility wears a mask of passivity -- is currently the number one source of men's problems in relationships and on the job. In Living with the Passive-Aggressive Man, Scott Wetzler draws upon numerous case histories...