Module 11 BEHAVIOR GENETICS AND EVOLUTIONARY PSYCHOLOGY

 Behavior Geneticists: researchers who study our differences and weigh the effects and interplay of heredity and environment.  Environment – every non-genetic influence, from pre-natal nutrition to the people and things around us BEHAVIOR GENETICS

 46 chromosomes – 23 from each parent  Chromosomes – threadlike structures made of DNA molecules that contain the genes  DNA – a complex molecule containing the genetic information that makes up the chromosomes.  Genes – the biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing a protein  Can be active(expressed) or inactive  Turned on by environmental events (stress, diet, drugs)  When turned on – provides the code for creating protein molecules, our biological building blocks  Genome – the complete instructions for making an organism, consisting of all the genetic material in the organism’s chromosomes GENES: OUR CODES FOR LIFE

 Identical twins – (monozygotic) develop from a single fertilized egg that splits in two, creating two genetically identical organisms  Placenta difference  Fraternal twins – (dizygotic) develop from separate fertilized eggs  Identical twins have more similar traits like outgoingness and emotional stability  Traits affect behaviors; makes them behaviorally more similar (ex) divorce rate TWIN AND ADOPTION STUDIES

 Separated twins: (Minnesota Twin Study)  Similar in taste, physical attributes, personality, abilities, attitudes, interests, fears despite different environments = strength of genetics  Critics: share an appearance and the response it evokes, placed in similar homes by adoption agencies, can fine similarities even in non-biological pairs  Adoptee studies: more similar to biological parents in extroversion/agreeableness  Environment has no discernable impact on their personalities TWIN AND ADOPTION STUDIES

 Why are children in the same family so different?  Gene difference?  Unique peer influences and life events?  Sibling relationships ricochet off each other amplifying their differences?  Differing genes lead to different personalities which evoke different responses in parents?  Parental influence: attitudes, values, manners, faith, & politics  Adoption beneficial: parents screened TWIN AND ADOPTIVE STUDIES

 Temperament – a person’s characteristic emotional reactivity and intensity  Present at birth  Biologically rooted and environmentally influenced  Variable heart rates, reactive nervous systems  (ex)Gene that regulates neurotransmitter serotonin which predisposes child to have a fearful temperament. Mix that with an unsupportive caregiver = inhibited child TEMPERAMENT AND HEREDITY

 Subfield in biology that studies the molecular structure and function of genes  Goal is to find some of the many genes that together orchestrate traits such as body weight, sexual orientation, and extraversion.  Purpose is to predict risk factors so steps can be taken to prevent problems before they happen  Find families with disorders across generations and compare DNA of those within a family that have the disorder with those that do not  Research can lead to finding potential problems in fetuses  Controversial - Labeling, discrimination, abortions MOLECULAR GENETICS

 The proportion of variation among individuals that we can attribute to genes (how much differences among people are attributable to genes)  As environments become more similar, heritability increases  As environments differ, heritability decreases HERITABILITY

 Most important human similarity is our enormous adaptive capacity  Interaction – the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity)  Epigenetics – the study of influences on gene expressions that occur without a DNA change (studying the molecular mechanisms by which environments trigger genetic expression)  Epigenetic mark – organic methyl molecules attracted to part of a DNA strand  It instructs the cell to ignore any gene present in the DNA stretch, thereby preventing the DNA from producing the protein coded by that gene.  Triggered by diet, drugs, stress GENE-ENVIRONMENT INTERACTION NATURE VIA NURTURE

 Studies how natural selection has shaped our traits and behavior tendencies.  Variations increasing the odds of reproducing and surviving are most likely to be passed on  Other variations arise from:  Mutations – a random error in gene replication that leads to a change  New gene combinations at conception EVOLUTIONARY PSYCHOLOGY

 Our behavioral and biological similarities arise from our shared human genome  We are more similar than we are different  More variation within a group of people than between a group of people  Similarities a result of natural selection – we have the traits that enable survival and reproduction  Mismatched with today’s environments  Irrational fears – spiders, snakes, airplanes over guns and electricity  Explains stranger anxiety, parental protection of children EVOLUTIONARY SUCCESS HELPS EXPLAIN SIMILARITIES

 Gender – in psychology, the biologically and socially influenced characteristics by which people define male and female  Different sexual views/behaviors  Goal to pass on genes  Women can’t reproduce as quickly as men – must incubate fetus  Attracted to mature, affluent, dominant men(ability to support and protect)  Men can spread seed quickly  Attracted to youthful women and with waists a third smaller than hips (fertile)  Women pair wisely, men pair widely EVOLUTIONARY EXPLANATION OF HUMAN SEXUALITY

 Hindsight explanation – look at effect and assume cause  Reinforces stereotypes of each gender – rationalizes behaviors  Ignores cultural influences and perceptions  Male/female behaviors may be result of environment not pre-wired  Doesn’t explain the relatively quick changes in sexual behaviors and views CRITICISMS OF EVOLUTIONARY THEORY