Slide 1The Evolutionary PerspectiveEvolutionary Developmental PsychologyGenetic FoundationsHuman Genome ProjectCell divisionGenetic FoundationsGenotype and PhenotypeDominant & Recessive InheritanceDominant-Recessive TraitsIncomplete DominancePolygenic InheritanceChromosomal AbnormalitiesGene-linked AbnormalitiesBehavior GeneticsHeritability IndexMeasuring HeritabilityHeredity & the Environment: Working togetherSlide 19Bi-directionality of genes and environmentGenotype x Environment (G x E) CorrelationsThe Epigenetic ViewGene X Environment (G x E) InteractionGene by environment interactionsBiological BeginningsThe Evolutionary Perspective •Natural selection•Evolutionary process•Individuals of a species that are best adapted are the ones that survive and reproduce•Evolutionary Psychology: Emphasizes the importance of adaptation, reproduction, and survival of the fittest in shaping behaviorEvolutionary Developmental Psychology •Using the concepts of evolutionary psychology to understand human development•Example: Human childhood period is extended•Issues:•Evolved mechanisms are not always adaptive in contemporary society•Cant test theory empirically•Bidirectional viewGenetic Foundations•Chromosomes •store and transmit genetic information•Genes •segments of DNA located along the chromosomes•DNA • complex double-helix molecule that contains genetic informationHuman Genome Project•Humans have approx. 20,000 genes •Human genome consists of many genes that collaborate•Activity of genes is affected by their environment•Stress, radiation, and temperature can influence gene expressionCell division•Mitosis: •Cell’s nucleus —including the chromosomes— duplicates itself and cell divides•Two new cells are formed, each containing the same DNA as the original cell•Meiosis: •Eggs and sperm (or gametes) are formed•Each has only ½ of the genetic material of the parent cellGenetic Foundations•Fertilization: an egg and a sperm fuse to create a single cell•Zygote: once-celled organism resulting from fertilization•Variability of genes•During meiosis genetic material switches chromosomes •Chance mutations in DNAGenotype and Phenotype•Genotype: all of a person’s genetic material •Phenotype: observable characteristics•Physical characteristics•Height, weight, and hair color•Psychological characteristics•Personality and intelligenceDominant & Recessive Inheritance•Dominant•Heterozygosity •Recessive•HomozygosityDominant-Recessive TraitsIncomplete Dominance•Both alleles of a single gene are expressed•Results in:•Combined trait or intermediate between the two•Pitch of male voicePolygenic Inheritance•Many genes combine to influence a trait.•Hair, height, nose, skin colorChromosomal AbnormalitiesGene-linked Abnormalities•Phenylketonuria (PKU) (1/10,000-20,000 births)•Metabolic disorder that, left untreated, causes mental retardation•Sickle-cell anemia (1/400 African American children)•Blood disorder that limits the body’s oxygen supply•Can cause joint swelling, as well as heart and kidney failure•Spina Bifida (1/500 births)•Neural tube defect resulting in brain and spine abnormalities•Cyctic Fibrosis (1/2000 births)•Glandular dysfunction that results in abnormal mucus production and hampered breathingBehavior Genetics•How does heredity and environment influence traits?•Heritability:•Statistical estimate of heritable influence on trait variance in a population•Portion of individual differences attributable to genetics•Ranges from 0 to 1.00Heritability IndexMeasuring Heritability•Family Studies•The degree to which biological relatives share traits•Adoption Studies•The degree to which adopted children resemble biological relatives or adopted family members•Twin Studies•Compares the degree to which monozygotic and dizygotic twins resemble each other for a traitHeredity & the Environment: Working together•Reaction range•Potential variation in a trait•Canalization•Heritable restrictions on the range of trait developmentThe Concept of Range of Reaction for Intellectual PerformanceIntellectual Performance (IQ)HighRestricted EnrichedAverageAveragechild A child B child CReaction RangeLowType of Environment?Bi-directionality of genes and environmentGenotype x Environment (G x E) Correlations•Environment reflects or reinforces genetic differencesPassive: Parents provide environment that fosters traitReactive or Evocative: based on their traits, children evoke different responses from othersActive or Niche Picking: choosing an environment that suits your traitsThe Epigenetic View •Development = bidirectional interchange between heredity and the environment •Heredity and environment collaborate to produce a person’s intelligence, temperament, height, weight, ability to pitch a baseball, ability to read, etc. (Gottlieb, Wahlsten, & Lickliter, 2006)Gene X Environment (G x E) Interaction •The interaction of a specific measured variation in DNA and a specific measured aspect of the environmentGene by environment interactionsnon-stressful environment stressful environment0123456789Genotype by environment interactionGENE AGENE