1. Psychology Ch. 2 The Biological Basis of Behavior Genes, Evolution, and Behavior

2. “Our brains, nervous system, and endocrine system keep us aware of what is happening outside (and inside) our bodies; enable us to use language, think, and solve problems; affect our emotions; and thus guide our behavior. To understand why they function as they do, we need to look at our genetic heritage, as individuals and as members of the human species.” pg. 80 Nature vs. Nurture: Heredity vs. Upbringing Genes vs. Environment

3. 2 Different but related fields address the influence of heredity on human behavior-
1. Behavior genetics:
 - Focuses on to which extent heredity accounts for individual differences in behavior and thinking.
Evolutionary Psychology:
- Studies the evolutionary roots of behaviors and mental processes- traits that all human beings share.

4. Genetics Def.- study of traits are transmitted from one generation to the next. Genes: Def.- Elements that control the transmission of traits; they are found on the chromosomes. “units of inheritance”

5. Chromosomes: Def.- Pairs of threadlike bodies with that contain the in the cell nucleus genes. - Every cell in your body contains enduring messages from your parents.

6. Each species has a constant number of chromosomes: Mice have 20 pairs Monkeys have 27 pairs. Human beings have 23 pairs of chromosomes in every normal cell. -one chromosome of each pair is contributed by each parent. Deoxyribonucleic acid (DNA): The main ingredient of chromosomes is DNA- a complex organic molecule that looks like two chains twisted around each other in a double helix pattern. DNA is the only known molecule that can replicate or reproduce itself, which happens each time a cell divides.

7. Human genome: Def. - a full complement of genes within a human cell
Human genome: Def.- a full complement of genes within a human cell. Dominant gene: Def.- member of a gene pair that controls the appearance of a certain trait. Recessive gene: Def.- member of a gene pair that can control the appearance of certain trait only if it is paired with another recessive gene.

8. Polygenic inheritance: Def
Polygenic inheritance: Def.- process by which several genes interact to produce a certain trait; responsible for our most important traits. -height -skin color -body type etc.

9. Behavior Genetics
Topics that interest all psychologists: perception, learning
& memory, motivation & emotions, personality, and
psychological disorders- but from a genetic perspective.
*Their goal is to identify what genes contribute to intelligence, temperament, talents, and other characteristics, as well as genetic predispositions to psychological & neurological disorders.
Animal Behavior Genetics:
Studies were it would be unethical or morally wrong to use humans in research.
Mice are used because they breed quickly and have relatively complex behavior patterns.

10. Strain studies:
Def.- studies of the heritability of behavioral traits using animals that have been inbred to produce strains that are genetically similar to each other.
Animals are raised together (same environment) but are different based upon their genetics.

11. Selection studies:
Def.- studies that estimate the heritability of a trait by breeding animals with other animals that have the same genetics.
Heritability is measured in terms of successive
generations that have the same trait-
Consider 15,000 years there were basically four types of dogs- today there is over 400 breeds.
Dogs are bred for specific traits (behaviors, appearance, manner, fur- hypoallergenic).

12. Human Behavior Genetics
Methods of studying behavioral techniques indirectly. 
Family studies:
Def.- studies of heritability in humans based on the assumptions that if genes influence a certain trait, close relatives should be more similar on that trait than distant relatives.

13. Family studies can indicate whether a trait runs in families
Family studies can indicate whether a trait runs in families. However, this correlation does not provide conclusive evidence that the trait is influenced by heredity.
Why not?
Family members generally share not only genes but also similar environment. The closer the relationship the more likely the family lived together compared to distant relatives.

14. Twin Studies:
Def.- studies of identical and fraternal twins to determine the relative influence of heredity & environment on human behavior.
Identical Twins:
Def.- twins developed from a single fertilized ovum and therefore identical in genetic make up at the time of conception.
-differences due to environment

15. Fraternal Twins: Def.- twins developed from two separate fertilized ova and there fore different genetic make up. Summary: Twin studies provide evidence for the heritability of a number of behaviors: verbal skills, aggressiveness, mannerisms, depression, or anxiety.

16. Adoption studies:
Def.- research carried out on children adopted at birth by parents not related to them- to determine the relative influence of heredity & environment on human behavior.
Please consider how individuals shape their own environments.