genetic explanation Flashcards
how do genes relate to aggression?
a person may be biologically predetermined to have biochemical differences
genes can determine levels of testosterone and the rate at which it is metabolised, as well as determining brain physiology in terms of the number of receptors and how sensitive such receptors are
what could differing brain physiology cause?
the pathway between the limbic system and the frontal cortex to be weak
how is the role of genetics in explaining aggression studied?
traditionally through twin, adoption or family studies, however since these are all naturally occurring, some research is done on animals that have been purposely bred
some research also uses animal isolation to remove the influence of social behaviour and imitation
why is it not certain that genes can cause aggression?
gene mapping has found no specific gene
a person may have a predisposition to aggression but that doesn’t mean they will portray it (genotype suggests aggression but the phenotype means its not shown)
what is the full name of the MAOA gene?
monoamine oxidase A
what does MAOA do?
the MAOA enzyme is controlled by the MAOA gene, and it breaks down important neurotransmitters including dopamine, noradrenaline and serotonin
what are the 2 types of MAOA?
MAOA-L (low-activity form)
MAOA-H (high activity form)
how does MAOA-L effect aggression?
higher levels of neurotransmitters because there’s not enough of the enzyme to mop them all up
(it appears that only men with the MAOA-L gene that were abused in childhood automatically display aggressive behaviour)
what was Brunner’s 1993 classic research on the MAOA gene?
‘Brunner syndrome’
monitored the urine samples of 5 men in a family in the Netherlands, finding they had an excess of monoamines caused my a MAOA deficiency
all the male family members had this genetic defect, and they all showed borderline mental retardation
research on the genetic explanation and the MAOA gene
-Moffitt et al 1992 - 442 new Zealand males aged 0-26, those who were abused and had MAOA-L were 9x more likely to engage in antisocial behaviour including aggression
briefly evaluate the genetic explanation for aggression
-MAOA gene can only attempt to explain aggression in those with MAOA-L, which is only 1/3 of men in western populations, so the others cant be accounted for this way
-it may be present in large numbers due to its evolutionary advantages eg risk taking behaviour which can make someone stand out at work
-interaction with the environment is important, as seen in abuse making it more likely the gene will present itself
-its an incomplete explanation
