Male and Female Differences
Lecture Outline - Psy 252
9/7/99
A. Sum up Importance of Replicators (Genes)
B. "Our Story"
C. What are Homo Sapiens Looking For?
Female:
good genes
resource display, earning capacity
committment: ability and willingness to invest in progeny
Male:
health and reproductive fitness
youth
beauty -- physical attractiveness
D. How do Humans Differ from Primate Mold?
All structural differences, all functional differences (behavioral differences) aimed at keeping the male around, cementing the pair bond.
1. Continuous receptivity of females.
2. Concealed estrus
3. Continuous intercourse
4. Female orgasm
5. Limited sperm
6. Female breasts
7. Tendency of females in a group to Synchronize Menstrual Periods
8. Brain dimorphisms (exceeded only by songbirds)
Different Structures--> Different Behaviors
E. Brain Dimorphisms Up Close and Personal
We are born with these brain differences, usually the different male and female behaviors that they generate are strengthened over time. Play to our "strengths".
1. Anterior part of the hypothalamus
In humans, pre-optic area 2X as large in men than in women
and contains 2X more cells in men.
--> Different Sexual Behavior
--> Differences in Aggressive Behavior
2. Bulbocavernosus Nucleus
Group of neurons in spinal cord, causing reflexes of the penis during copulation, arousal.
Show dramatic sexual differences.
Adult males have 200 neurons in this nucleus,
females fewer than 70.
Present in both sexes early in development.
Atrophy in females directly related to absence of androgens.
If females given androgens during the critical period of development, increased # of neurons.
Males deprived of androgens have #’s equal to females.
Androgens regulate the number of neurons by preventing cell death.
3. Cerebral Cortex
In females, left hemisphere is thicker than the right.
Females use the "whole" brain (fmri), less specialized.
verbal ability. more fluent. don’t usually stutter.
receive wider range of sensory info
hear better, see better in dark.,
more sensitive to acute pain, more resistant to chronic pain
read earlier, better at grammer, punctuation, spelling
better at foreign languages
better at picking up social cues, feeling emotional
In males, the right cortex is thicker than the left.
Male brains more specialized
better at mathematics
better at seeing patterns and abstract relations
(general strategic rather than detail) -- chess
superior eye-hand coordination
spatial ability
see better in daylight
more self-centered, less emotional display
4. Corpus callosum (splenium) is thicker in females.
Basis of intuition? Better Switchgear.
5. Anterior Commisure is larger in females.