Transcript Evolutionary Psychology - Raleigh Charter High School

Evolutionary
Psychology
The study of evolutionary
explanations for shared
human behaviors.
Topics in Evolutionary Psychology
 Why
do humans tend to pair off
monogamously?
 Why do babies tend to develop
stranger anxiety at about the same
age (8-13 mo.)?
 Why are people more likely to
develop a phobia of spiders than of
guns?
Evolutionary psychologists use
natural selection to explain
behaviors.
 What
is natural selection?
– (1) Genetic differences between
individuals in a species causes (2) some
organisms to be better suited to their
environment. (3)These organisms are
more likely to survive and pass on their
genes so (4)these traits become more
common in successive generations.
Why does stranger anxiety appear
between 8-13 mo?
1.
Genetic mutations create variation in
when stranger anxiety appears:
1. 0 months
2. 3 months
3. 6 months
4. 9 months
5. 1 year
6. 2 years
7. 3 years
8. Never
(For simplicity, assume stranger anxiety persists
for 6-8 months from onset.)
Why does stranger anxiety appear
between 8-13 mo?
In what way are the infants that
develop stranger anxiety at 9-12
months better suited to their
environment?
 0-6 months – what is the danger in
getting stranger anxiety too early?
 2 years-never – what is the danger
in getting stranger anxiety too late?
Your turn:
Develop an evolutionary hypothesis for
the following common human
behavior:
Children protest going to bed.
Evolutionary Psych Data
1. 5-year-old
1-year-old
2. 40-year-old
20-year-old
3. Older
Younger
4. Good financial prospects
An attractive body
Good-looking face
Ambition and industriousness
Caring personality
Exciting personality
5. a. Father
Mother
b. Parents of father
Parents of mother
c. Younger parents
Older parents
6. a. Death of a son
b. Death of an unhealthy child
Death of a daughter
Death of a healthy child
Gender Differences in
Reproduction
Women
•
•
•
Sure the baby is hers
Invests lots of time/energy
into each child
Can only make one baby
per 9 month period
(usually)
Men
• Less sure the baby is his
• May invest very little time and
energy into each child
•Have virtually unlimited
reproductive potential
Therefore, it is in the woman’s best interest to be choosy
about who she mates with, picking only men who are 1) likely
to have good genes, and 2) willing and able to provide for her
and the child.
How does a women know?
Good looks often indicates good genes.
- Masculinized physical features
correlates positively with better
immune function.
- Facial symmetry indicates lack of
parasite infection.
How does a women know?
- Feminized facial features correlate
positively a greater willingness to
help raise children.
-So do we look for masculine or
feminine features?
-It depends.
Mate selection and the menstrual
cycle
% feminization preferred
Menstrual Cycle Alters Face Preference
25
20
15
Japanese Faces
Caucasian Faces
10
5
0
Low conception High conception
risk
risk
Darwin Award
Honoring those who improve the
species...by
accidentally removing themselves
from it!