Agression Flashcards
Chagnon
Observed a Amazonian rainforest tribe. Men who had killed/gone to battle had a higher status than those who did not. Mates were easier to come by, They were able to continue their gene pool through procreation
Caldini 1976
Studied uni sports teams, if the team was winning, students were far more likely to show support by wearing team colours. Suggests that by doing so their status increases by association, and may be more attractive to females
Motelica Heino
Male mice castrated at birth (before CTP) showed decreased levels of aggression even if given huge doses as adults. Those castrated after 10 days (after CTP) difference in aggression much less marked.
Simpson
When testosterone was replaced by hormone replacement therapy in castrated animals, aggression increased to pre castration levels.
Sapolsky
3rd monkey in dominance hierarchy given higher levels of testosterone than top monkey. Levels of aggression increased although, directed at those lower in the hierarchy. Exaggerates aggression, does not cause it.
Klinesmith 2006
Participants given either a gun or a toy to reassemble. Salvia taken to measure testosterone levels. Found that gun control had 100 x more testosterone than toy control. Then asked to place chilli into drink of the next participant. Gun control gave 3x more chilli. Suggests external stimuli increases aggression levels and testosterone as a result.
Females hyenas
Wild females are more aggressive and socially dominant than males ( sex reversal ). They secrete more testosterone. However captive hyenas when compared are much less aggressive, suggesting testosterone doesn’t cause aggression, suggesting environmental influences.
Nannini
Asked make and female participants wether they would be more distressed by their partner having a night of passionate sex with another person (sexual infidelity) or forming a deep long lasting bond with someone else (emotional infidelity). Men were more bothered by sexual infidelity and women by emotional, supporting the idea that our reactions to infidelity arise through desires to meet evolutionary aims.
Shackleford
The use of mate retention strategies such as vigilance and direct guarding correlated with the use of aggression. Suggesting that aggression may have arisen as another mate retention strategy, used to deter infidelity supporting the evolutionary explanation.
Theilgaard
Compared the genotype XYY with a control group and XXY genotype and found no evidence of XYY causing extra aggression.
Turner
Found that aggression in pigs is a moderately heritable trait and it can be passed onto offspring.
Cases et al
Could identify 9 violent members of a Dutch family tracing back to 1870. It was found that they carried a rare MAOA gene mutation on the X chromosome leading to low levels of MAOA and excess levels of neurotransmitters in urine
Caspi
Carried out a longitudinal study in New Zealand. Participants were identified as having low or high levels of MAOA, they also recorded upbringing (maltreatment and abuse) and anti social behaviour. Found that the MAOA gene variant had no effect on its own, only in circumstances of abused children. Abused men were 3x likely to commit violent crime. High levels of MAOA seem to promote trauma resistance against maltreatment experienced in childhood.
Mednick
Used adoption studies to compare similarities of adoptees aggression levels with their biological parents ( shared genes ) and their adoptive parents ( shared environment) Identified the rate of criminal convictions amongst 14000 male adoptees in Holland. He found that in families where neither parents had any criminal conviction or only adoptive parents had convictions the conviction rate for the subjects was lower than in subjects where the biological parents had displayed criminal behaviour, empathising the role of genetics in aggressive behaviour.
