1. BEHAVIORAL GENETICS
AND EVOLUTIONARY
PSYCHOLOGY

2. Genetics
 We have 23 pairs of
chromosomes
 Half from genetic
mother, half from
genetic father
 What do genes do?

3. Function of genes
 Chromosome is made
of genes
 Each gene codes for
a protein
 Genes can be turned
“on” or “off”

4. How similar are we?
 Humans are 99.9%
similar
 Humans and Chimps
are 96% similar
 Humans and
bananas are 50%
similar!

5. Twin Studies
 Twin studies examine
similarities and
differences between
identical and fraternal
twins
 Identical twins are far
more similar than
fraternal

6. Separated at Birth?
 Famous example:
The Jim Twins
 Same name, same
wives, same pets,
same hobbies, same
habits
 Could this just be
coincidence?

7. Adoption Studies
 Another fantastic way
to examine the
impact of genes and
environment.
 Personalities- largely
genetic
 Then why are
siblings so different?

8. Temperament
 Difficult
 10%
 Easy
 40%
 Slow to warm up
 15%
 Identical twins have more
similar temperaments

9. Gene Environment Interactions
 Environment triggers gene activity
 Gene activity influences the environment
 Temperament as an example?
 Choosing environments

10. Evolutionary Psychology
 What makes us similar?
 What is natural selection?
 Not just “survival of the fittest”
 Grandpa Simpson: I used to be with it, but then
they changed what it was. Now what I'm with isn't
it, and what's it seems weird and scary to me. It'll
happen to you...

11. Selection
 Environmental
Pressures
 Sexual Pressures
 Domestication and
Breeding

12. Why has evolution made us fat?

13. Gender Differences
 It’s all about the sex!
 Men are more likely
to be sexually liberal
 Women are more
likely to be sexually
conservative