Genetics, Evolutionary Psychology, and Behavior 3C

Behavior Genetics: Predicting Individual Differences Behavior Geneticists - study our differences and weigh the relative effects of heredity and environment on behavior and personality.

Nurture and Human Diversity Environment: Parents Prenatal Experience Peer Influence Culture Gender

Genes: Our Codes for Life DNA (deoxyribonucleic) – complex molecule containing the genetic info that makes up the chromosome. Chromosomes – threadlike structures made up of DNA molecules that contain genes Any genetic basis for a trait are located in chromosomes 23 from mother and 23 from father Located within bone cells

Genes: Our Codes for Life Genes - small segments of DNA that are the biochemical units of heredity. Capable of synthesizing a protein One or more genes are responsible for expression or repression of a particular trait

Genome Genome - set of complete instructions for making an organism, containing all the genes in that organism. human genome makes us human the genome for drosophila makes it a common house fly.

The threadlike structures that contain genes are called Genomes Synapses Neurons Chromosomes Hormones 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

DNA is a complex Molecule Synapse Gene Genome Neuron 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

The biochemical units of heredity that make up the chromosomes are called Genomes Molecular genetics Heredity Behavior geneticists genes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Studying the effects of heredity and environment on twins Twin Biology Studying the effects of heredity and environment on twins Identical twins raised together - share the same portion of the chromosomes that determines a single trait or ____________ Identical twins raised apart – same genes, different environment Fraternal twins – different genes, same environment

Identical Twins Studies Twin Studies Temperament, Intelligence Abilities, Attitudes Interests, Fears Brain Waves, Heart Rate Caution: any two strangers are likely to share coincidental similarities.

IdenticalTwins and IQ Bouchard Study .69 Correlational coefficient for IQ tests of identical twins raised apart. .88 raised together.

Twins and Personality Temperament - a person’s stable emotional reactivity and intensity…part of your personality that you are born with. Extroverted (outgoing) & fearless v. Introverted (shy) & cautious Identical twins express similar temperaments

Separated Identical Twins and Personality Identical Twins separated at birth – no extreme differences in personality Differences between fraternal twins are greater than identical twins. Twin Studies Temperament, Intelligence Abilities, Attitudes Interests, Fears Brain Waves, Heart Rate Bob Sacha

Adoption Studies Adoptees - Personalities are different from their adoptive parents and siblings. Environment shared by a family’s children has relatively no impact on their personalities

Personality Big 5 Traits Extroversion – outgoing Agreeableness - cooperative and compassionate Conscientiousness – self-disciplined Neuroticism – negative emotions Openness – willingness to experience new things

Twins Studies

Parental Influence Parents do influence: Attitudes Values Manners Faith politics

Heritability Heritability refers to the extent to which the differences among people are attributable to genes Heritability is numerical value with a range from 0.0 to 1.0 0 = genes do not contribute at all to individual differences High environmentability 1.0 = genes are the only reason for individual differences High heritability For human behavior, almost all estimates of heritability are in the moderate range of .30 to .60. Applies to populations not individuals Two boys raised in a barrel with identical environmental conditions would have a heritability of ______?

Heritability and Big 5 Big 5 Traits Heritability Extroversion .67 Agreeableness .52 Conscientiousness .59 Neuroticism .48 Openness .63

Gene-Environment Interaction Genes and environment affect our traits individually, but more important are their interactive effects. Alessia Pierdomenico/Reuters/Corbis Rex Features People respond differently to Rowan Atkinson (Mr. Bean) than Orlando bloom.

Twins Studies

The New Frontier: Molecular Genetics Molecular genetics is a branch extension of behavior genetics that asks the question, “Do genes influence behavior?” It seeks to identify the specific genes influencing behavior

Genetic predispositions Studies of identical twins who had been reared apart most clearly highlight the importance of ________ in personality development. Natural selection Mutation Adoptive relatives Home environments Genetic predispositions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Adoptive parents are most likely to influence the ________ of their adopted children. Adult height Political attitudes Adult weight Extraversion personality 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Heritability refers to the extent to which Unrelated individuals share common genes An obtain result occurred by chance Nurture controls a trait rather than nature Infant personality determines adult personality Variation among individuals can be attributed to their differing genes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Molecular genetics seeks to Identify specific genes influencing behavior Assess the relative contributions of nature and nurture Focus mainly on what makes us so much alike as humans Treat individuals with mental disorders Design machines that interact best with people 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Evolutionary Psychology Evolutionary psychology - studies the evolution of behavior and mind using principles of natural selection. Adaptive behaviors are those that promote reproductive success .

Natural Selection Natural selection - evolutionary process through which adaptive traits are passed on to ongoing generations because these traits help animals survive and reproduce.

Examples Fear of Heights Fear of the Dark Fear of ostracism Overeating

L.N. Trur, American Scientist (1999) 87: 160-169 Artificial Selection Biologists like Belyaev and Trut (1999) were able to artificially rear and domesticate wild foxes, selecting them for friendly traits. L.N. Trur, American Scientist (1999) 87: 160-169 Any trait that is favored naturally or artificially spreads to future generations.

Question (summarized) Human Sexuality Gender Differences in Sexuality Question (summarized) Male Female Casual sex 60% 35% Sex for affection 25% 48% Think about sex everyday 54% 19%

Mating Preferences Females Select one male because of the higher costs involved with pregnancy, nursing and childcare. Look for maturity, dominance, affluence and boldness Males Mate with multiple females to spread genes Look for youthful appearance and at ages associated with peak fertility. If older wants younger women IF teenager want women a few yrs. older

Criticisms of Evolutionary Psych Works backwards to propose and explanation Underestimates cultural expectations on human sexual behavior Unethical and immoral men could use explanations to rationalize behavior toward women Does not consider the importance of individual choices

Explain how an evolutionary psychologist might explain why humans developed into omnivores, eating both meat and plants.