| | | quote | Originally posted by loafer87gt:
The 'Violence Iniative Project" revealed that blacks have significantly higher amounts of testosterone and serotonin in their systems, hard wiring them for violence. Unfortunately, these studies had to be abandoned as the program was deemed to be discriminatory.
http://discovermagazine.com.../violencegenesand446
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Among them were some exploring the link between aggressive behavior and disturbances in levels of a chemical called serotonin. Gerald L. Brown, a psychiatrist who is clinical director of the National Institute on Alcohol Abuse and Alcoholism, explains that serotonin transmits nerve signals in the brain and is important in regulating sleep, sexual behavior, appetite, and impulsivity. In 1979 Brown was part of the team that first suggested an association between low levels of serotonin and out-of-control aggressive behavior in a group of U.S. military men. Serotonin depletion appears to have a disinhibiting effect, says Brown, and studies have repeatedly implicated it in explosive, destructive, impulsive behavior, including suicide. "A more familiar word might be violent," he adds, "but violent is not a scientific term; it's descriptive."
Many things can apparently influence serotonin production, though race isn't one of them. Serotonin levels are 20 to 30 percent lower in men than in women. They are high in newborns, low in adolescents, then rise again with age--a pattern that seems to fit with the stereotype of the impulsive teenager. A diet high in L-tryptophan, an amino acid needed to make serotonin, can boost levels of the neurotransmitter in animals. Some studies tentatively suggest that animals subjected to stressful environments make less serotonin, raising the possibility that the same might happen in humans living under the gun, whether on the battlefield or in poor, crime-ridden neighborhoods.
http://www.ncbi.nlm.nih.gov...articles/PMC2612120/Impulsive aggression is a complex behavioral phenotype and multiple brain systems may contribute to its etiology and its high comorbidity with other disorders. The association between impulsive aggression and its comorbid disorders may result from biological predisposing factors, such as an imbalance among the functions of different neurochemical systems, or dysfunction in activities of executive brain regions.
Specifically, low levels of the neurotransmitter serotonin (5-HT) have been associated with impulsive aggression in both human and animal studies (Asberg, Scalling, Trakeman-Bendz, & Wagner, 1987; Linnoila & Virkkunen, 1992). A number of studies indicate that serotonin and dopamine (DA) systems interact closely at a basic neurophysiological level (Daw, Kakade, & Dayan, 2002; Kapur & Remington, 1996; Wong, Feng, & Teo, 1995), and that impairment of the serotonin system function can lead to dysregulation of the dopamine system (De Simoni, Dal Toso, Fodritto, Sokola, & Algeri, 1987). Additionally, activation of the prefrontal cortex (PFC), specifically the orbital and ventromedial PFC, has been implicated in the behavioral control of aggression, and impairments in these areas are related to an increase in impulsive aggression (Anderson, Bechara, Damasio, Tranel, & Damasio, 1999; Davidson, Putnam, & Larson, 2000). These lines of evidence suggest that aggression and its comorbid disorders may come from an underlying neurobiology, specifically serotonin and dopamine interaction in the prefrontal cortex. Other biological factors, such as norepineprine (Barrett, Edinger, & Siegel, 1990) and testosterone (Giammanco, Tabacchi, Giammanco, Di Majo, & La Guardia, 2005) may also contribute to aggression. However, the focus will be on the interaction between serotonin and dopamine, because of their well-established relations with impulsive aggression and their significance in explaining comorbid disorders.
http://www.scientificameric...esnt-cause-violence/[Historically,] researchers expected an increase in testosterone levels to inevitably lead to more aggression, and this didn't reliably occur," says Frank McAndrew, a professor of psychology at Knox College in Galesburg, Ill. Indeed, the latest research about testosterone and aggression indicates that there's only a weak connection between the two. And when aggression is more narrowly defined as simple physical violence, the connection all but disappears.
Changes in testosterone levels in response to challenges can be further shaped by our expectations. In one experiment that put a biological spin on the red state–blue state divide, researchers at the University of Michigan at Ann Arbor had a volunteer "accidentally" bump into and then insult men who were raised either in the North or the South. The researchers hypothesized that Southerners come from a "culture of honor" in which aggressive responses to insults are culturally appropriate, and the results of their experiment bolstered that notion: Not only were Southerners more likely than their northern counterparts to respond with aggression, but their levels of testosterone also rose as a result. The Northerners, in contrast, were much less likely to experience an increase in testosterone.
| | | quote | Originally posted by loafer87gt:
In addition, scientists have identified five genes in blacks known to contribute to violent behavior. A 2010 study on these genes concluded that these predict criminality and violence more accurately than child's relationship with his mother.
http://takimag.com/article/.../print#axzz2yau0CrOt
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http://bjp.rcpsych.org/content/198/6/457.longn 2002, Caspi and colleagues published a paper examining the role of the monoamine oxidase A gene (MAOA) in the development of antisocial behaviours.1 This research was motivated by earlier evidence suggesting that carriers of the low-activity variant of MAOA were an at-risk group for criminality and violence.2– 4 Using data from the Dunedin Multidisciplinary Health and Development Study (DMHDS) Caspi et al were able to show consistent gene×environment (G×E) interactions between exposures to childhood maltreatment and MAOA genotype in the development of antisocial behaviours. Their findings showed that associations between childhood maltreatment and antisocial behaviour were modified by MAOA, with those having the low-activity variant being more responsive to the effects of maltreatment than the high-activity group.
http://www.pnas.org/content/106/7/2118.fullThere is some evidence of a main effect for genotype and some evidence for a gene by environment interaction, such that MAOA is less associated with the occurrence of aggression in a low provocation condition, but significantly predicts such behavior in a high provocation situation.
[This message has been edited by Fiero_Fan_88 (edited 04-11-2014).]
