2.  Builds on what we know about the differences between species and applies these concepts to studying humans  Deals with understanding how both genetics and the environment contribute to human behavior

3.  Located in the nucleus of each human cell  Hereditary units composed of a sequence of DNA  Hold the info needed to create the proteins required by all types of living creatures  These proteins determine how the organism looks and behaves

4.  All the genes have been identified for humans, chimpanzees and macaque monkeys  Role of specific genes in specific behavior remains unknown  Chimpanzees share 98% of the same DNA as humans  Macaque monkeys share 93%

5.  Researchers can now triangulate to learn what genes primates share and what genes are uniquely human  It’s likely that many differences between man and closely related primates lie NOT in gene sequence but in the regulation of the expression of those genes  Animal research can be conducted to identify genetic influences on behavior and can possibly generalize to humans

6.  Genes are inherited but are not typically directly responsible for behavior  There is no single cause and effect relationship between genes and behavior  Role of specific genes in specific behaviors remains unknown

7.  Williams Syndrome  Parents have a 50% chance of transmitting this disorder to their offspring  Caused by a micro-deletion on the long arm of chromosome 7s  Behaviors: strengths in recognizing faces, expressing themselves verbally, and musical talent  Weaknesses: visual-spatial construction tasks, high rates of anxiety and phobias

8.  Behavior will not be manifested without appropriate environmental stimuli  Diathesis-stress model: ◦ Used to explain the origin of depression ◦ Argues that depression is the result of a “genetic vulnerability” and traumatic environmental stimuli in early childhood ◦ Some children don’t become depressed after a traumatic experience, whereas siblings do ◦ Demonstrates no single cause-and-effect relationship between genes and behavior

9. How studies show evidence of a Genetic Basis for Behavior  The studies try to determine the extent of genetic influence on particular behavior  They show correlations between behaviors and genetic inheritance  If the heritability of a behavior is high, then individuals who share more genes should have high concordance rates for a behavior (shown in twin studies)

10.  In MZ studies (identical twins): 100% of the genes are the same, so any difference in behavior is attributed to the environment  In adoption studies, researchers can conclude that the common behaviors are attributed to the environment, since they do not share the same genes

12.  Compiled data from 111 studies of IQ correlation  Examined identical twins-reared apart for 100% genetic relationship baseline  Results-found that the closer the kinship, the higher the correlation for IQ  Concluded-any similarities are attributed to genetics

13. Compared intelligence and other factors between self-selected sample of MZs reared together vs apart

14.  Results: ◦ Same person tested twice = 87% ◦ Identical twins reared together = 86% ◦ Identical twins reared apart = 76% ◦ Fraternal twins reared together = 55% ◦ Biological siblings reared together = 47%  Conclusions: Heritability estimate for IQ is 70% with only 30% due to environmental factors.

15.  High ecological validity-participants from around the world  Mean age=41, NOT adolescents  Huge sample size

16.  Ethical concerns on how he reunited the twins  No control of frequency of contact b/n twins prior to study  Can’t assume twins raised together experience the same environment (equal environment assumption)  All twins were white, from industrialized middle-class

17.  Challenged the criticism of “equal environment assumption”  Compared IQ of adopted children and natural children  Adopted children were from poor, lower class, lower IQ parents and were adopted by parents who were wealthy, white, middle class, with a high IQ.  Assumptions: children have the same upbringing, same environment, same parents

18.  Differences in IQ should be attributed to genes  Results: no difference in IQs  Conclusions: environment has a stronger impact on IQ than previously believed  Supported the assumption that these children are in an equal environment

19.  Adoption studies in France  Infants from low SES families went to high SES families  Results: IQ score increased 12-16 points in childhood  Conclusions: ◦ an enriched environment may increase IQ in children ◦ It is likely that there is a strong interaction between genes and the environment

20.  Intelligence is difficult to define and measure  IQ concordance rates between parents and children increase over time, which suggests that possibly children choose similar environments as their parents increasing the similarity of IQ  Average IQ score is increasing-possibly due to exposure to changes in technology and environmental demands compared to years before-again supporting the role of environment on IQ