Steven Crane Compiled Section Handouts. Human Behavioral Biology 2012

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?

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  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.
  

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  Females have more androgens, have clitorises like penises, fat pads like scrotums.
  

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  Their social system has females on top. They also give birth to only 2 cubs. What do you predict for their feeding order?
  

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  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.
  
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  It might also be about depression. How could you explain that with hormones?
  

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  Drop in progesterone near the end of the cycle.
  
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  Progesterone potentiates GABA, as you should recall.
  
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  Opioid levels also drop around the period.