a) Living in a rural area
b) Being an alpha male and having just lost a fight to the #2 male c) Having a particular version of the MAO enzyme
d) Drinking large quantities of alcohol
e) Increased sensitivity of testosterone receptors in amygdala f) Being subjected to child abuse
c. After more extensive physical and psychological tests and background checks, you conclude that this patient is 100% fine. No pre-existing genetic tendencies towards aggression, no environmental factors, no biological basis. Despite killing 34 people, no criminal charges are pressed against him. Given what you learned about aggression in class, why might the man have killed 34 people? (1 pt)
Aggression II
Neurochemistry of aggression (seconds before the aggressive behavior)
What is the driving force giving your frontal cortex the power to do the harder but right thing?
Dopamine
Serotonin time
What are low levels of serotonin associated with?
Impulsive behavior. Impulsive aggression.
How does serotonin synthesis inform our understanding of its role in aggression?
Serotonin is made from tryptophan. The enzyme that does this conversion is TH.
When serotonin acts in a synapse, it is then either reuptaken or degraded by MAOb, an enzyme.
So these actually contradict the "serotonin = impulsive aggression" story. How so?
Poor MAOb variant means more serotonin will act in the synapse. But people with this variant have more antisocial behavior.
And if TH works better you should have more serotonin. But people with better TH tend to have more impulsive violence.
So it's complicated, m'kay?
Where else do MAOb variants come in?
The New Zealand kids study.
The "good" version makes you less vulnerable to developing antisocial behavior.
The "bad" version (less effective at degrading serotonin, leaving more in the synapse) predicts more antisocial behavior. With more aggressive childhoods, more antisocial behavior. Need childhood abuse to make it happen. It's a vulnerability. Gene-environment interaction.
What effect does alcohol have on aggression?
Same story that comes up over and over: it exacerbates pre-existing tendencies. Makes unaggressive individuals less aggressive. Makes aggressive individuals more aggressive.
Also see this play out with cultures newly introduced to alcohol. They adopt the drunken behavior of the drunken role models of their colonial occupiers.
What are the two profiles of alcoholism?
Profile 1: Increases risk of antisocial behavior. Drinking socially. Men.
Reaching age 30 and you're cured.
Profile 2: no gender difference. Alcoholism most severe in late middle age. Barely functioning alcoholics drinking alone.
Heritability separates out the two lines.
Acute environmental triggers of aggression: Releasing Stimuli
What are some primate releasing stimuli for aggression?
Stress, pain, and frustration.
Taking out aggression on those under you works out great for baboons' stress levels. Might explain something about your future boss…
Ex: rape seen in baboons in cases of displaced aggression after alpha male jerks are dumped off their thrones.
Does crowding cause aggression?
Same story that comes up over and over: it exacerbates pre-existing tendencies. Makes unaggressive individuals less aggressive. Makes aggressive individuals more aggressive.
Hormones in adulthood influencing aggression
What does testosterone have to do with aggression?
SAME story as with T and sexual behavior
So elevated T within normal physiological ranges does not cause increased aggressive behavior.
Could you say T causes aggression?
No! It's about modulating aggression. Add T to the amygdala (and do nothing else) and it doesn't fire more, but when it is stimulated from some other structure, far more likely to fire.
What is the challenge hypothesis for aggression?
T generates aggression when resources are being challenged.
But it also generates pro-social behavior if being pro-social is what it takes to defend resources.
More cooperation in the ultimatum game where you have to be prosocial to win money (a resource).
Who is our big exception to typical sex patterns in T and aggression? What are the patterns in this exception?
Spotted hyenas.
Females have more androgens, have clitorises like penises, fat pads like scrotums.
Their social system has females on top. They also give birth to only 2 cubs. What do you predict for their feeding order?
Now cubs go first, then females, then males.
Opposite of how it is in lions.
How do we explain PMS?
Some hypotheses about it being a myth, invented by the west, a "dependent" personality style, a conflict between being productive and reproductive etc.
Bleh to all that. Baboons have the same profile of irritability/aggression so it's probably biological. AND males have the same mood shifts along with female partners' periods so it can't just be the hormones.
So it's biology within a social context.
It might also be about depression. How could you explain that with hormones?
Drop in progesterone near the end of the cycle.
Progesterone potentiates GABA, as you should recall.
Opioid levels also drop around the period.
Long-term environmental effects on aggression
How does Lorenz' hydraulic model of aggression hold up to scrutiny?
It would say aggression is inevitable, and should be less likely after previous aggression.
But aggression is NOT inevitable. And aggression tends to beget more aggression.
How about the frustration-aggression Marxist hypothesis?
Holds up well. A lot like displacement theories.
Exception: aggression goes down during periods of famine, of scarcity. This would argue that aggression is more behavioral fat.
How about behaviorist accounts of aggression?
This would predict it's all about reinforcers: rewards and punishments. That will determine aggression.
Sort of true: premeditated crimes are influenced by penalties. But crimes of passion are not.
Human infants develop ego boundaries, theory of mind, self/other distinctions.
These as precursors for empathy and pro-social behavior.
Necessary but not sufficient, as seen with sociopaths who have great theory of mind
Does violent TV make kids more aggressive?
Same story that comes up over and over: it exacerbates pre-existing tendencies. Makes unaggressive individuals less aggressive. Makes aggressive individuals more aggressive.
How do you respond to the claim that violence is biologically predetermined, since aggressive violence peaks in adolescent males?
You'd bring up the data comparing murder rates in Chicago/Toronto/London.
They all follow the same rates of violence curves.
But the absolute amount of violence is hugely culturally determined.
Take-Home Point: your long-term environment teaches you the social contexts that are appropriate for violence.
Huge predictor of violence: living in a culture that rationalizes violence