Aggression

Neural and Hormonal Mechanisms

• Serotonin
• its a neurotransmitter- low levels of serotonin means there is less control over impulses and thoughts so therefore someone is likely to be more aggressive. It is thought that it works in the orbital frontal cortex in the Lombok system (amygdala).
• + 16 males convicted of murder were compared to males who attempted suicide and normal males. They found lower levels of serotonin and 5HIAA (A by product of serotonin) in those who had killed someone or attempted suicide. BUT this is beta bias and androcentricism
• + changed diets of one group so that it included tryptophan which is needed to produce serotonin. Low amounts of tryptophan and serotonin had a high tendency to be aggressive
• - biological reductionism
• - focuses on correlational relationship
• Limbic System
• this is a collection of structures in the centre of the brain. The destruction of the hypothalamus on limbic system causes aggression, stimulation of amygdala causes aggression
• + PET scans of 41 murderers and 41 controls found abnormalities in the functioning of limbic system
• - socially sensitive: murderers can use this excuse to receive a lower sentence
• - 14yr old acting aggressively- found a tumour in the limbic system
• - biological determinism
• Testosterone
• sex hormone which is 8 x higher in males than females- it regulates social behaviour. It is thought to be the cause of men being more aggressive than women. The enzyme aromatise, when lacking, testosterone is less likely to be activated. Plus high levels of testosterone is thought to decrease serotonin levels
• + castrated mice injected with testosterone
• + more aggressive sports men played, the higher levels of testosterone found
• + saliva and spinal fluid used to measure levels- highly scientific and no bias
• - studies mainly focus on men, andocentricism
• - correlational

Genetic Factors of Aggression

• Twin Studies
• MZ and DZ twins- in a questionnaire of hostility, MZ had 50% concordance but DZ had 19%
• MAOA Gene
• MAOA is an enzyme that breaks down neurotransmitters after a nerve impulse. The quantity of it is controlled by MAOA gene. Found that less MAOA, less breakdown of neurotransmitters and therefore higher aggression- this is known as the warrior gene.
• + Brunned studies men in one family with the warrior gene. Found large amounts of neurotransmitters in men's urine samples and found all had high levels of aggression. BUT only one family and all males
• + Found that people who had committed intimate partner violence had low activity MAOA gene
• - nature and nurture debate: the gene is from nature but studies have found it is only activated from childhood dofficulties
• - men with the warrior gene, some are not aggressive

Ethnological Explanation

• Inmate Releasing Mechanism
• Fixed Action Pattern

Evolutionary Explanations

• + high violence rates found between partners that are just about to leave or are cohabiting- suggests jealousy
• + research found that women are more physically attracted to men who display dominant behaviour
• - biological determinism
• - suggests aggression is excusbale