1. Is it all in the genes? NARTURE
Heredity and Behavior
Is it all in the genes? NARTURE

2. Behavioral Genetics- an interdisciplinary field that studies the influence of genetic factors on behavioral traits

3. Chromosomes and Genes
Chromosomes are strands of DNA molecules that carry genetic information
Every cell in the human body contains 46 chromosomes (except sex cells) 23 pairs (each parent)
Zygote- a single cell formed by the union of a sperm and an egg
Genes are the DNA segments that serve as the key functional units in the hereditary transmission

4. Why don’t family members look the same?
Each parents 23 chromosomes can be scrambled in over 3 million different ways, yielding over 8 million configurations
Homozygous condition –two genes in a specific pair are the same
Heterozygous condition – two genes in a specific pair are different

5. Dominant Gene expressed when paired genes are different
Recessive Gene one that is masked when paired genes are different
Detached earlobe (D) Attached (R)

6. Genotype vs. Phenotype Genotype- a person’s genetic makeup
Determined at conception/fixed
Phenotype- how a person’s genotype is manifested in observable characteristics
may change over time/modified by environmental factors

7. Polygenic Inheritance
Characteristics that are influenced by more than one pair of genes
3/5 gene pairs determine skin color

8. Research Methods We can’t manipulate and do selective breeding on humans
Family Studies- researchers assess hereditary influence by examining blood relatives to see how much they resemble one another on a specific trait
Schizophrenic studies
Also indicate whether or not a trait runs in a family

9. Twin Studies- researchers assess hereditary influence by comparing the resemblance of identical twins and fraternal twins with respect to a trait
Identical Twins (monozygotic twins) emerge from 1 zygote that splits for unknown reasons
Fraternal Twins (dizygotic twins) result when two eggs are fertilized simultaneously by different sperm cells, form two separate zygotes
Useful because we can look at environmental conditions

10. Adoption Studies- assess heredity influence by examining the resemblance between adopted children and their adoptive parents
Genetic/environmental influence on traits

11. Genetic Mapping- the process of determining the location and chemical sequence of specific genes on specific chromosomes
Human Genome project
Researchers seek to determine things such as the genetic basis for intelligence, extroversion, schizophrenia, musical ability, and other behavioral traits
Virtually all behavioral traits tend to be polygenic and are shaped by many genes

12. The Evolutionary Bases of behavior

13. Darwin Natural selection Organisms vary in a variety of ways
Some characteristics are heritable
Variations in heredity are the basis of evolution
Fitness- refers to the reproductive success of an individual organism relative to the average reproductive success of the population
Variations in reproductive success are what actually fuels evolutionary change

14. Natural Selection posits that heritable characteristics that provide a survival or reproductive advantage are more likely than alternative characteristics to be passed on to subsequent generations and thus come to be ‘selected’ over time.
Populations NOT individuals and a gradual occurance

15. Refinements to Evolutionary Theory
Adaptation- an inherited characteristic that increased in a population(through natural selection) because it helped solve a problem of survival or reproduction during the time it emerged
(preference for fatty foods)
Inclusive fitness- sum of an individual’s own reproductive success plus the effects the organism has on the reproductive success of related others
Self-sacrifice for the good of your genes (so they can survive)

16. Behaviors as Adaptive Traits
Behavioral traits as well as physical are adaptive
Behavioral maneuvers
Hiding
Trading sex for material goods that an aid survival