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4 - Genes, Evolution and Behaviour.docx

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Department
Psychology
Course
Psychology 1000
Professor
Dr.Mike
Semester
Fall

Description
Chapter 4 Genes Evolution and Behaviour 1 Genetic Influences  Genetic endowment + environmental forces  behaviour  Nature (something we are born with) vs nurture (something we learn) o Environment can influence protein synthesis o Genes determine range of possibilities but not the degree of expression Chromosomes and Genes  Hippocrates suggested that semen contains some sort of design for offspring  Mendel used garden peas o Show heredity involves passing on specific organic factors  Genotype: set of genes inherited  Phenotype: observable characteristics produced by that genetic endowment o Can be affected by other genes and by the environment o Cannot infer genotype from phenotype  Chromosome: tightly coiled molecule of DNA that is partly covered by protein  Genes: DNA portion of chromosomes that carry the hereditary blueprint  Alleles: alternative forms of a gene that produce different characteristics  There are no genes for a particular attribute o Measure of intelligence = measure of reaction time (fast response of neurons = ↑ intelligence?) Dominant, Recessive and Polygenic Effects  Genotype and phenotype are not identical because some genes are dominant and others are recessive  Dominant: particular characteristic that it controls will be displayed  Recessive: characteristic will not show up unless both genes inherited are recessive  Polygenic Transmission: number of gene pairs combine their influences to create a single phenotypic trait  Homozygous Allele: phenotypic outcome predictable  Heterozygous Allele: phenotypic outcome may not be predictable Genetic Engineering: The Edge of Creation  Recombinant DNA procedures: certain enzymes cut DNA into pieces & combine them with DNA from another o Produced the human growth hormone  Insert new genetic material into viruses that can infiltrate neurons and modify their genetic structure  Gene Knockout: alter a gene in a way to prevent it from carrying normal functions o Test animals to see if neurons did not respond to neurotransmitter, what will it affect? o Disadvantage: very few behaviours are controlled by a single gene Behaviour Genetics Techniques  Heritability coefficient: variation in a characteristic within a group can be attributed to genetic factors o Applies to within a group and not between groups as different factors affect different groups o h = variance due to genes / total variance o h = 0.0 (due to environment diversity) = 1.0 (due to genes, genetic diversity) o does NOT indicate extent to which genes are responsible for expression of trait o hair colour in inuit  everybody has that hair colour in the population  genes are responsible for the trait but no variability  heritability is 0 (due to environment)  Family relationship studies  Concordance: (co-occurrence) characteristic o Identical twins 100% o Fraternal twins, parents, siblings 50% that has higher co-occurrence in highly o Grandparent, uncle, aunt 25% related people o First cousin 12.5%  Adoption Study: study if adopted child if more similar to biological or adoptive parent 2  Twin Studies: monozygotic (identical twins) and dizygotic (fraternal) growing up in different environment  Galton: Hereditary Genius o Assumed that intelligent successful men had intelligent successful sons  But not the same for intelligent successful men and adopted sons  Measures simple motor and sensory abilities  Believes that intelligence was unitary (mental quickness)  Invented correlation coefficient  Results disappointing - didn’t find correlation  Sir Cyril Burt o Large sc2le study of twins reared apart in separate environment o Reports h approaching 1.0 (genes) but faked data  Bouchard’s Twin Studies and finding long lost twin o Identical twins, apart 0.72 2 o Identical twins, together 0.86  H = 0.72 o Fraternal twins, together 0.60 o Not saying that IQ is genetically determined o Siblings, together 0.47  Of the observed variability in measured IQ, we can o Adopted sibs, together 0.34 o Same person 0.87 attribute to 72% genetic factors  Scarr and Carter – Saltzman (1979) o Important assumption  No environmental differences for identicals vs fraternals  Treat identicals different than fraternals o Twins who thought they were identical (whether true or not) were more alike o Twins who though they were fraternal (whether true or not) were less alike Genetic Counselling  Provides counselling, support and medical information about genetic disorders and risks to patients and families  Good to test and monitor diseases, pregnancy, new born What is the cause of genetic disorders? Single Gene Disorders o Enlarged ventricles, cortical  PKU degeneration o Recessive gene on autosome 12 o Dominant  offspring has 50% chance o Occurrence: 1 in 10,000 of acquiring o Lack enzyme; phenylalanine  tyrosine o Detection possible through gene o brain damage  mental retardation mapping o Effectively treated by diet  Tay Sachs Disease Sex-linked disorders o Recessive gene on pair 15  Men are more susceptible than women because o Occurrence: 1 in 3600 (Eastern Europe) y chromosome is shorter (less information) o Lack enzyme to break down fatty acids  XXX, Xy, Xyy – phenotypically male o Normal development at birth  Blind, deaf, unable to swallow, Down syndrome (chromosomal mutation in meiosis) muscle atrophy, mental damage  Nervous system abnormality  retardation  Fatal by age 4  Physical appearance (mongolism)  Huntington’s  Due to accumulation of amyloid protein (also in o Rare dominant gene on autosome pair 4 Alzheimer’s) o Occurrence: 1 in 16 000 o Plaques and neurons die o On set 35 – 45 years o Can alleviate symptoms with intense  At first: clumsy, forgetful cognitive stimulation  Progressive deterioration:  Incidence related to mother’s (and dad’s) age muscle control (chorea), I.Q., o Risk about 1 in 1000 brain, terminal in 10 – 20 years o Past 40, 6 in 1000 3 Genetic Influences on Behaviour Heredity, Environment and Intelligence  differences in intelligence due to genetic factors and environment  Genetic argument o The more genes people have in common, the more similar they are in IQ  Environment argument o Twins and siblings raised together have more similar IQs Biological Reaction Range, the Environment, Personality and Intelligence  Reaction Range: genetically influenced trait is the range of possibilities  one inherits a range for potential intelligence and environment will determine where they are in the boundaries Behaviour, Genetics and Personality  Hans Eysenck was the first modern personality theorists o Personality differences could be traced to differences in brain development or function  Five Factor Model – personality trait theory of Robert McCrae and Paul Costa o Extraversion-Introversion (sociable, outgoing, adventuresome vs quiet, inhibited, solitary) o Agreeableness (cooperative, helpful, good-natured vs antagonistic, uncooperative, suspicious) o Conscientiousness (responsible? goal directed? dependable? careless?) o Neuroticism (worrying, anxious, emotionally unstable vs well adjusted, secure, calm) o Openness to experience (imaginative, artistically sensitive vs unreflective, lacking in intellectual curiosity)  Identical twins may be more alike o People treat them the same o Parents dress them up in identical clothes  Identical twin experiment where they are raised in different environments o Variation attributable to genetic factors o Variation due to a shared family environment among those reared together o Variation attributable to other factors due to unique individual personal experiences o Proven that they are more similar even raised in different environments o Genetic factors and individual experience most influenced o Twins have heritability coefficients all greater than 0.5 Conclusion  Genetic, environmental and personal experiences are all equally important to personality characteristics The Neuroscience and Genetics of Dyslexia  Dyslexia: difficulty learning to read  Genetic contribution to the entire range of reading ability  Spelling and phonological coding (ability to translate letters and syllables into sounds)  Specific dyslexia susceptibility gene on chromosome 6  Chromosome 1, 2, 3, 6, 15 and 18 influence reading ability o Not a sex-linked disorder  Gene variants associated with dyslexia influence brain development and later brain function o Hard to do experiment  Reading out loud does not mean you are reading the word right  Reading silently, uncertain if you read it correct in your head  Less activation that controls in two area of the left temporal lobe 4 Evolution and Behaviour  Evolutionary psychology - how behaviour have evolved over millions of years in response to environment o no behaviour can occur without environment impacting Evolution  1 day = 9.6 million years  Mid nov – vertebrates  11:54 on 31 – homo sapiens  Jan – life begins  Dec 11 – mammals  Overall, we haven’t been  Feb-oct – nothing much  19 - birds around for a long time happening  Dec 24 – primates Darwin  He didn’t want to publish his discovery o Humans were related to apes and other creatures in the world Evolution of Adaptive Mechanisms Evolution  change over time in number of particular genes and characteristics they produce in an interbreeding population  some genetic variations through mutations, random, accidents during mitosis  mutations help create variation and variation is needed for evolution Natural Selection  characteristics that increase the likelihood of survival and ability to reproduce within a particular environment o more likely to survive and become more common over time  neutral variation/evolutionary noise (random variations) is preserved for future environmental demand Evolutionary Adaptations  products of natural selection  allow organism to meet recurring environmental challenges to their survival, thereby ↑ reproductive ability  organism’s biology  behavioural capabilities and its behaviour (mental abilities)  whether it will survive  theory 1 o forced apelike animals from trees to hunt on open plains o survival greater for bipedal locomotion (walk on 2 legs) o freeing their hands to use as weapons o hunting encouraged social organization o language developed o Australopithecus (early ancestor)  homo erectus  Neanderthal  Brain size tripled o domain specific adaptations: designed to solve a particular problem  human brain is all purpose problem solver  Proximal vs distal causes Distal  Proximal o Proximal – immediate, what causes behaviour now  Evolutionary history of species o Distal – evolutionary process  Distal  Individual DNA  Inherited traits o Very functional – changing to meet environmental needs  Social development  Ultimately everything is due to the genes but  Emotional reaction info processing  Phenotype does not mean genotype  Traits not necessarily due to natural selection (psychology – closer to proximal)  Phenomenological experience  No natural selection o Genetic drift  Founder effect… chance (geographic)  Restricted gene pool of species (e.g. due to migration) o Correlates of structure - other related trait selected 5 An Evolutionary Snapshot of Human Nature  Language – infants exposed to language at a younger age  human bonding with caregiver – recognize human faces  need to belong – make cooperative relationships with a group became critical to survival & reproductive success  helpful – altruism increases with degree of genetic relatedness  emotions – social communication  personal adaptations to life – learning & experience Evolutionary Psychology Personality  Evolutionary Personality Theory: how biological factors contribute to diff between personality traits o Extraversion, emotional stability helpful in mate selection o Conscientiousness and agreeableness important to group survival and reproduction o Openness to experience for problem solving and creative activities Mating Systems and Parental Investment  Produce lots of offspring and offer little or no care E.g. fish  Produce few offspring, offer care, protection until independently survive on their own E.g. humans, mammals  Parental Investment: the time, effort, energy and risk associated with caring successfully for each offspring o Sex with more investment is more discriminant and more competed for o Sex difference – egg and sperm, pregnancy and breast feeding o Polygyny: more than one wife  More female investment and polygyny  Male investment low to maximize fitness to reproduce with different females  Species with more polygyny are larger males relatives to females  Females are more discriminating since they have limited eggs o Monogamous mating system: equal or approximately equal parental investment e.g. birds  Natural selection would favour genes that lead to parents staying together  Both parents investment leads to lower competition o Polyandry: one female mates with many males (rare)  Females are larger and more aggressive than males since they are competing for their mates o Polygynandry: (promiscuity) all members of the group mate with all other members eg. chimpanzees  Can help reduce competition for a mate Mate Preference  Both genders - mutual attraction, dependability and emotional stability  Men - emphasize more on physical attractiveness (consistent in every culture) o Good hea
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