-Genetic Base of Intelligence
Next Time: Evolution
Scan: Finish Chapter 4
1) How do I estimate heritability?
2) Is intelligence heritable?
3) What is the cause of genetic disorders?
---> traits related to action of more than 1 gene or chromosome.
h^2 = variance due to genes / total variance
---> estimate of how much observed variability due to genetic factors alone
h^2 = 0.0 (due to Environment)
= 1.0 (due to Genes)
---> does NOT indicate extent to which genes are responsible for expression of
---> taps relative contribution of genes to overall variation in population
---> applies to groups, NOT to individuals Note
---> If h^2 = 0, genes are still responsible for expression of traits
---> h^2 increases as genetic diversity increases
---> h^2 decreases as environmental diversity increases
Heritability of Intelligence
Notion Seems Reasonable
Family Relationship Studies
Identical Twins 100%
Fraternal Twins 50%
Parent, Sibling 50%
Uncle, Aunt 25%
1st Cousin 12.5%
---> Family - Relationship Studies
- remarkable similarity
Jim Lewis and Jim Springer Galton: Hereditary Genius
---> 1869 ---> relatives of intelligent people
---> measures simple motor and sensory abilities