Lecture outline:

Boys, Girls, & Brains

I. Sex Differences in the Brain:  

1, 2, 3                                                                  

Males and females share roughly 99.8% of their genes

II. The nature of the brain:

• Plasticity
• Your brain is what you do with it
• "The older boys and girls are, the less confidently we can determine that their differences are the result of genes and hormones."
  • “they germinate from basic instincts and initial biases in brain function, but each of these traits is massively amplified by the different sorts of practice, role models, and reinforcement that boys and girls are exposed to from birth onward.” (7)
• Epigenetic - the environment acting on or through our genes
  • Height/weight
  • Language
    

III. The misuse of neuroscience -

• The delicacy of scientific standards - what makes a good study?
• "It's sexy to find difference" - file drawer effect
• Misrepresentation by media

IIIx. The Difference value

0.2 Small difference
0.5 Medium difference
0.8 Large difference

"The Gender Similarities Hypothesis" --Dr. Janet Hyde, U Wisconsin

Lueptow Study - U of Akron, Ohio

Summing up

What factors affect our perception of male and female differences?

• Human penchant for extremes, stereotypes
• Media misrepresentation
• Media overrepresentation
• Capitalist profitseeking - gendering products

On to the womb

What makes a boy?

• Y chromosome, and the SRY
• Testosterone, and the Anti-Mullerian Hormone
• More testosterone, peeking at 14-16 weeks (AIS)
  

What makes a girl?

• DAX1 gene on X chromosome
• Estrogen, not active til after birth
  
  
  

Intersexual stories

• David Reimer, changed at 18 mos
• 1998 case, changed at 7 mos.
• CAH Congenital adrenal hyperplasia

Sex Detectives:

• finger-length ratios
• not prenatal movement, heartrate, etc.

On the fragility of boys

• conception ratio 170:100
• maturity