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1XX3 Psychology Notes.docx

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PSYCH 1XX3
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Joe Kim

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1XX3 Psychology Notes 1/9/2013 11:43:00 AM January 14, 2013 – Development 1 Module 1 – Introduction to Psychology 1XX3 Introduction: Multiple levels of analysis including human though and behaviour Overview: 1XX3 covers learning, cognition, and social psychology; depression  Foundational Topics: o Development: gene-environment interactions across an individual‟s lifespan; biological basis of thought and behaviour; provides a working framework with testable hypotheses and tools to create knowledge and understanding for the problems of psychology, neuroscience, and behaviour o Evolution: gene-environment interactions across an individual‟s lifespan o Neuroscience: the study of the nervous system; neural basis of thought and behaviour Module 2 – Introduction to Development Introduction to Development Definition of Development: the changes and continuity that occur within the individual between conception and death; how you change over time and how you stay the same Definition of Maturation: biologically-timed unfolding of the changes within the individual according to that individual‟s genetically-determined plan; influenced by specific environmental conditions Definition of Learning: the acquisition of neuronal representations of new information; relatively permanent changes in our thoughts, behaviours, and feelings as a result of our experiences  Allows us to acquire new thoughts, behaviours, and feelings  Enduring changes in thoughts, feelings, and behaviours  Ability to respond appropriately to stimuli and events  Learned processes can be controlled and so practiced that they become automatic (oversight) Interactionist Perspective (maturation and learning interact): the view that holds that maturation and learning interact during development; most developmental changes reflect the interaction  Maturation: some essential systems must be in place before learning proceeds  Learning: ability to walk once muscles have developed through maturation; without some minimal level of input to learn from the world, maturation will be absent or delayed (child in dark room) Module 3 – Introduction to Studying Development Introduction to Studying Development:  Dramatic changes early in life: infancy and childhood; more than later in life; development that takes place in early years play an important role in shaping who you become  Four ways to measure abilities in infants: o Habituation Procedure: detects if an infant can detect the difference between two stimuli; test ability to discriminate between 2 stimuli  Habituation: a decrease in the responsiveness to a stimulus following its repeated presentation  Dishabituation: an increase in the responsiveness to a stimulus that is somehow different from the habituated stimulus (distinguishing new stimulus from old ones)  Infants show interest in novel objects in environment  Process begins by repeatedly presenting infant with same stimulus while measuring changes in physiological responses (heart rate/breathing rate etc.)  Infant will initially show activity but decreases over repeated exposure (they recognize it as the same stimulus and no longer show interest)  If child cannot discriminate the squares, the novel square will be irrelevant = no change in response o Event related potentials (ERP): a measure of the brain electrical activity evoked by the presentation of stimuli  Special cap of electrodes is placed on the head to detect electric activity in brain neurons  Visual stimulus affects occipital lobe  Auditory affects temporal lobe  Habituation and ERP provide complementary behavioural and neural measures to understand infants sensory interactions with environment o High amplitude sucking method: measured by special pacifier; infant controls presentation of stimulus to measure preference  Measure baseline sucking rate for infant in absence of relevant stimuli  Sucking determines the length of stimulus (pleasant = longer sucking, unpleasant = stop sucking) o The preference method: measures infants likes and dislikes; amount of time an infant chooses to attend to different stimuli  Infant is placed in looking chamber facing 2 stimuli and the researcher measures the attention the infant pays to each stimuli (find preference)  Infants prefer big pattern with lots of black vs. white contrasts than faces  Conclusions to Studying Development: o Inferences and assumptions: researchers make inferences about complex cognitive perceptual primarily from carefully observed behaviours (validity) o The competence-performance distinction: an individual may fail at a task not because they lack those cognitive abilities, but because they are unable to demonstrate those abilities  Researchers may use a research technique that doesn‟t properly measure their variable of interest, given their subject pool  Researchers may incorrectly conclude that an infant does not possess an ability that they actually do Module 4 – Introduction to Developmental Research Methods Introduction to Developmental Research Methods – repeated measures over time; tracking changes over time introduces the need to use some unique experimental designs  Looking at how abilities change over time  Remembering a list of numbers vs. remembering a list of numbers changes with age Two Developmental Research Designs  The longitudinal design: a developmental research design in which the same individuals are studied repeatedly over some subset of their lifespan; allows researchers to assess developmental change o Used less frequently in the real world o Track each person over time as they develop o Uncover any links between how they did early in life with how they did later in life o Find patterns that are common to all people  Disadvantages of longitudinal design: o Selective Attrition: loss of participants in a study such that the sample ends up being non-responsive of the population as a whole; some participants may quit, be unfit to continue, or may die = different sample at different time points o Practice Effects: changes in participants‟ responses due to repeated testing; subjects may improve performance based on prior exposure alone, rather than natural development over time of the skills being studied  Cross-sectional Design: a developmental research design in which individuals from different age groups are studied at the same point in time o This study may allow a researcher to formulate some unlikely developmental trends o Relatively less time consuming and expensive; can uncover age differences o Disadvantages: cannot distinguish age effects from gene rational effects; cannot directly assess individual developmental change o Combine longitudinal and cross-sectional designs to combine weakest features and strongest features of both design types in one 1XX3 Psychology Notes 1/9/2013 11:43:00 AM January 14, 2013 – Development 2 Module 1 – Introduction to Hereditary Transmission Introduction to Hereditary Transmission – fundamental ways in which genes and environment interact to shape who you become  Genes inherited from parents affect maturation and development Chromosomes and Genes  Zygotes: when a sperm penetrates an ovum, a new cell is formed (zygote); contains 46 chromosomes (23 from each parent)  Human Chromosomes: a threadlike structure that is made from DNA  DNA and Genes: segments of DNA comprise genes, which provide the chemical code for development; chromosomes contain between 30000-40000 genes (Human Genome Project) Cell Division – zygote divides at an exponential rate until at birth you have billions of cells with same 46 chromosomes  Genetic recombination  Monozygotic twins: same sperm and ovum; genetically identical; formed one zygote and then split into two separate zygotes  Dizygotic twins: different sperm and ovum; share 50% of genes; start off as two different zygotes from the moment of conception Sex Chromosomes – men determine the gender of the child  Autosomes: we have 23 pairs of chromosomes, including 22 autosomes rd  Sex chromosomes: 23 pair chromosomes determines person‟s gender  Offspring inherit an X chromosome from mother and an X or Y from father: female carries 2 X chromosomes while the male carries an X and a Y chromosome; mother always passes on an X (XX = female, XY = male) From Genotype to Phenotype – 46 identical chromosomes I each cell translates in to 30000-40000 genes to make up a genotype  Definition of genotype: an individuals inherited genes  Definition of phenotype: the expression of an individual‟s genotype in terms of observable characteristics  4 patterns of genetic expression: expression of genotype into phenotype follow several patterns of inheritance (siblings with different eye colours) o Simple Dominant-Recessive Inheritance: a pattern of inheritance in which the expression of a trait is determined by a single pair of alleles (eye colour)  Alleles: expression of a trait is determined by a single pair of genes  Homozygous: when two alleles have the same effect on the phenotype (2 alleles are the same)  Heterozygous: when two alleles have a different effect on the phenotype (2 alleles are different)  Dominant allele is expressed in the phenotype  Recessive allele not expressed by still heritable (one pair of genes/alleles determines trait expression)  Phenotypic expression of a trait is expressed by multiple pairs of genes (eye colour) o Polygenetic Inheritance: when multiple genes are involved in the expression of a trait  Height and weight are determined by interaction of multiple genes  No single gene can account for most complex behaviours  Several genes contribute to the expression of a trait, often showing large variation (IQ) o Codominance: two dominant alleles are both fully and equally expressed to produce a phenotype that is a compromise between two genes  Two alleles are both expressed to produce an intermediate or combined phenotype  ABO blood type (A and B are dominant and O is recessive): offspring expresses both equally resulting in AB blood type o Sex-linked Inheritance: genes expressed on X chromosome; results in traits more often expressed in males than females  XY male inherits X from mother and Y from father, and XX female inherits X from each of her parents  Some recessive genes expressed on the X chromosome are responsible for disorders like colour blindness and hemophilia  Because females have two X chromosomes, the phenotypic expression of recessive alleles occurs less frequently in females relative to males, who only have one X chromosome  Females rarely express sex-linked recessive gene disorder in their phenotype, although they are often genetic carriers Module 2 – Introduction to the Interactionist Perspective Introduction to the Interactionist Perspective – nature vs. nurture: the extent to which genetics and environmental factors contribute to how a person develops  The extreme behaviourist point of view: nurture is all-important and that a person‟s development was largely independent of genetic factors; behaviourist Watson suggested that with proper environmental control and training, any individual can be made into a predetermined occupation  The genetic point of view: scientists believed that you become who you are by predetermined inherited genes and the environment had little effect Nature and Nurture  Canalization Principle: Genotype restricts the phenotype to a small number of possible developmental outcomes; some developmental processes are buffered against environmental variability o Genetic and environmental factors interact to produce complex traits such as intelligence o Psychologists agree that nature and nurture interact to produce the expression of individual traits and are now interested in the extent to which nature and nurture drive individual traits  The Babbling Example: All infants babble in the same way making similar sounds, regardless of the culture; universal phonemic sensitivity is independent of the environment o It is only later that cultural influences shape the final phonemes selected to remain  The Range of Reaction Principle: An individual genotype establishes a range of possible responses to different kinds of life experiences  The Height Example: Height is a phenotypic trait that is clearly influenced by the interaction of genes and the environment o Final height is determined by factors including proper nutrition, sleep and exercise during development o Potential range of height across poor and optimal conditions is determined by genetic factors o Genes determine range of potentials for different traits, and the input that you receive from your environment influences how your genotype is expressed as a phenotype Three Ways Genes Influence Environmental Experiences  Passive Correlations: the environment that parents choose to raise their children in was influenced by the parents‟ own genes o Environment chosen by parents is likely to mesh well with the inherited genetic potential of the child o Occurs early in lifetime  Evocative Correlations: the traits that we have inherited affect how others react to and behave towards us o Genes can affect how others react to and behave towards you (natural temperament influences how others behave towards you) o Occurs throughout lifetime  Active Correlations: our genotype influence the kinds of environment that we seek o Actively choose an environment that satisfies personal needs o Occurs late in lifetime  Changes over the lifespan – the influence of each of these gene-environment interactions changes across lifespan o Early in life, passive genotype/environment correlations influence you the most when you cannot choose your own environment o Active genotype/environment correlations begin to play a larger role in your development in childhood and continues into adulthood as you have more opportunities to make decisions o The way that your inherited traits affects how others respond to you via evocative genotype/environment correlations can be influential throughout your lifespan The Logic of Twin Studies – Intelligence correlation in monozygotic and dizygotic twins  Because both types of twins normally develop in the same environment at the same time, you can assume that if monozygotic twins are more similar for a trait than are dizygotic twins, the difference is presumably due more to genetic factors o Average correlation for monozygotic twins is 0.86, but 0.6 for dizygotic twins; such differences suggest the degree to which genes or environment contribute to a particular trait Module 3 – Introduction to the Critical Periods Introduction to Critical Periods – parents choose environment in which to raise a child  Super-babies through classical music o Playing classical music/reading aloud to fetus while pregnant  Definition of a critical period: a window of opportunity within an individual‟s development in which particular environmental stimulation is necessary in order to see permanent changes in specific abilities  Possible reason why parents go overboard with offering early stimulation  After a critical period, the same environmental stimulation will not have the same benefit Evidence for Critical Periods in Development  Visual deprivation in kittens: when kitten 1 was deprived of vision for first 4-6 weeks of life, it becomes permanently unable to discriminate visual patterns properly; no amount of visual stimulation following this critical period can help them to regain normal visual abilities o Kitten 2 was visually deprived for same amount of time as kitten 1, but only after having reached 4 weeks of age; therefore his visual abilities are unaffected by period of deprivation and discrimination of visual input is normal  Together, critical period in visual development is in the first 4-6 weeks of life; early input is necessary  Fragile period: visual input is necessary for normal visual pathways to be established  Enriched environments: differences in brain structure were observed in rats raised in either enriched or deprived environments o More social stimulation leads to more connections between neurons The Implications of the Leap in Thinking  Without normal stimulation, the brain loses some function  Can affect parental decisions, adoption, and child intervention policy  Does more early stimulation equal more brain development? o Likely to affect parental decisions, could affect decisions to adopt, and affects public policy on child intervention (overstimulating child before they are born) o It is possible that children exposed to extra stimulation before they‟re ready may actually withdraw and lose interest in learning Problems with Critical Period Evidence  Based on extreme cases  Doesn‟t look at enriched environments  Extra stimulation is not always better  More synapses? – during early development, we actually start out with an excess # of synapses in the brain which are pruned when we develop o Relationship between enhanced synaptic growth and intelligence is unclear o Brain circuitry remains malleable throughout lifespan (you continue to learn new skills later in life) o Lifelong plasticity Two Types of Brain Growth  Experience-expectant brain growth: our brains have evolved to expect a certain amount of environmental input, and with this input, our brains develop normally o Ordinary levels of visual, auditory, and social input ensure the brain develops properly  Experience-dependent brain growth: our brains develop according to our own personal experiences o Brain growth is specific to each individual and reflects the more subtle changes in brain structure across individuals based on their varied experiences Sensitive Periods  Sensitive periods: brain maintains some capacity for change and growth in adulthood; our brains develop according to our own personal experiences  Flexibility in the timing and type of stimulation required for normal development o This change reflects our enriched understanding of these phenomena o There is greater flexibility o Less specificity in the exact type of stimulation necessary for development to proceed normally 1XX3 Psychology Notes 1/9/2013 11:43:00 AM January 21, 2013 – Evolution 1 Module 1 – Introduction to Adaptations: relevance of evolutionary biology for psychological sciences Biological Sciences – biology is the science of life, so psychology is obviously a biological science  Evolution is the unifying theory  Biological science and psych have the goal to elucidate the adaptive designs of living things o The working parts/functional systems/subsystems that animals are made up of Module 2 – Adaptations Adaptations  Definition of Adaptation: adaptations are biological traits that help an individual to survive and reproduce in its habitat o Adaptations perform a specific function o Always “for” something o Make an organism better suited to its environment  Adaptation examples o Human Eye: enables us to recognize and respond effectively by detecting and analyzing reflected light o Raccoons: nocturnal animals that have good night vision, but also have sensitive front paws that “see” through touch as they scavenge for food o Bats: adaptation has enabled them to navigate through their environment at night with their sophisticated echolocation system; bats discriminate easily between a falling leaf and a moth  Adaptationists: biological traits aren‟t simply morphological; perceptual processes and behaviours are also biological adaptations o Adaptationists are scientists that use this label to describe how hypotheses about adaptive function guide their investigations (psychologist who study development, behaviours or perceptual systems are adaptationists too) o Hypotheses re: adaptive functions  Psychological Adaptations: o Higher mental processes: they refer to the tasks that the mind needs to accomplish to do its job (adaptive functions of mental activity) o Cognitive psychologists are adaptationists – they find it helpful to analyze their subject matter into adaptive problems or tasks and then look for adaptations that solve those problems  Selective attention  Memory encoding  Memory retrieval  Word recognition o Can function be considered for psychological adaptations?  Adaptations Conclusions – adaptations evolve through natural selection Module 3 – Evolution by Natural Selection Introduction to Natural Selection – adaptations emerge in development as a result of the activation of relevant genes in interaction with relevant aspects of the environment  How do adaptations arise?  How are they maintained? Darwin and Wallace – discovered natural selection (one of four basic mechanism of evolution)  Others are mutation, genetic drift, and migration  Differential survival and reproduction  Three essential components to their insight o Natural Selection: differential survival and reproduction of organisms as a result of the heritable differences between them; straight-forward concept that is misunderstood o Three Essential Components:  Individual Differences: within any population, there is variation among individuals for any given characteristic  Differential Reproduction: these differences affect individual‟s chances of surviving and reproducing, causing differential reproduction (some people have more offspring)  Heritability: the traits that give rise to differential reproduction have a genetic basis – offspring of successful reproducers will resemble their parents with respect to these variable characteristic Example of Selective Transmission  Red fish, blue fish, one fish, 2x fish? – red fish get eaten more easily because they are more visible  Which traits are going to be reproduced at the highest rate? o Blue fish because red fish get killed off  Selective Transmission: o Variation in traits + Differential reproduction + Heredity = Evolution by natural selection o Over-successive generations, there will be successive transmission of heritable parental traits and the population will mostly be blue  Specific characteristics that are best adapted for survival and reproduced at higher rates  Eventually entire population will be blue Module 4 – Natural Selection in the Wild Stabilizing Selection – selection against any sort of departure from the species-typical adaptive design  Keeps traits stable over generations Darwin‟s Finches  Galapagos Islands: evolution of the beak shape and size in a particular species of Darwin‟s finches (Medium Ground-Finch that lives on Daphne Island)  Peter and Rosemary Grant: studied these birds, along with their students, were able to observe natural selection in action within only a generation Natural Selection in Darwin‟s Finches  Drought: in 1977, a drought decimated vegetation; left only tough seeds usually left alone by finches‟ birds with big beaks survived while small-beaked birds died from starvation  Change in average beak size: from 1976 to 1978, average beak depth increased from 9.4mm to 10.2mm o Large-beaked survivors reproduce when conditions were favourable for breeding and because beak size is heritable, their offspring inherited large beaks as well Natural Selection in the Wild Conclusions  Return to Pre-drought Beak Size: when the drought ended and plants again produced smaller seeds, average beak size of finches returned to pre-drought size  Most changes observable in our lifetime tend to be small  Permanent changes can lead to speciation Module 5 – Reproductive Success = Fitness Adaptations Promote Reproductive Success  Survival of the fittest  Natural selection favours reproducers: not just those who are best at surviving, but those who are best at reproducing Darwinian Fitness – average reproductive success of a genotype relative to alternative genotypes  Fittest individual is not always smartest, biggest, or fastest  Fitness is a label for the abstract property that natural selection tends to maximize  Reproductive Success Gene Frequencies  Change in gene frequencies  Evolution as a change in gene frequencies over generations o This is how evolutionary biologists define evolution Module 6 – Sexual Selection  Most organisms typically reproduce sexually (fusion of female and male gametes) Courtship Displays  Peacock, Elk: peacock flashes colours to attract a mate o Whatever male succeeds will father the children  Sexual Selection: there is usually competition for mates and natural selection acts on mate-finding and reproductive behaviours  Peacock courtship display: o Energetically expensive to produce; no help at all to physical survival o More conspicuous to predators o Harder to get away from predators o Increases risk of dying o However, does contribute to fitness via increased chance of mating; he sheds tail at end of breeding season and grows a new one for the next season  It‟s a matter of reproduction, not survival o Sexual selection: the component of natural selection that acts on traits that influence an organisms ability to obtain a mate Mating competition:  Elk: stag who win contest against its rivals will get to monopolize a harem of females o Only males have antlers and musculature to withstand these fights  Weaponry: males don‟t have as much stamina for running away from predators and can get stuck in deep snow o They shed their antlers until mating season comes again Two Subtypes of Sexual Selection  Mate choice and mating competition: point is to charm the opposite sex o If an anatomical trait differs between the sexes, it may be a sexually selected trait o Sex difference only exists in breeding season o You can tell by appearance whether they have a weapon or display features  Sexually Selected Traits: o Both traits have negative effect on survival  If you can dominate your rivals and keep them from you mates by physical force, then your mates can only choose you o For the elk: antlers are used in combat (weapon) o For the peacock: tail-feathers are used courtship (display feature)  Sexual Selection: the component of natural selection (the differential reproduction of types) that results from differential access to mates o Being chosen by the opposite sex (female choice) o Defeating same-sex rivals in mating competition (success in combat) o Eye-spots on peacock tails have experimentally shown that females discriminate between males on the basis of the number of eye spots  More is better  Also prefer males with good left/right symmetry o Mate Choice: female choice picks out males with best resistance to diseases; best genes for being healthy  In humans, levels of interest in breast size and how deep a males voice is continue to rise every year in regards to appeal Module 7 – Species-Typical Behaviour and the Comparative Approach Species-Typical Behaviour: behaviours are evolved, species specific adaptations  Test hypotheses about adaptive functions  Behaviours are adaptations: the recognition that behaviour is an evolved characteristic of a given species was the starting point for the modern science of animal behaviour  Birds can be differentiated by their vocalizations, dietary and habitat preferences o Physical form (typography) o Habitat preference o Group size o Social system  Sigal Balshine: this professor studies these features comparatively, in different species of fishes o Animal species differ in family functions, and any of these attributes is likely to reflect adaptations and to be something that can potentially evolve Behaviour Genetics  Darwin, dog breeding and pigeon fanciers o You can keep animals in captivity and selectively breed those who are most or at least aggressive or whatever trait you like  Dog breeders can breed dogs to do any sort of task  Reuven Dukas (cognitive ecology): this professor studies the evolution of learning and used of fruit flies (drosophila) as a model system General Conclusions  Evolution is fundamental to the study of psychology  Living organisms comprise evolved adaptations, unique to each species o Each adaptation serves an identifiable function in the life of an organism and has over evolutionary time, made a positive contribution to its fitness by making it better suited to its specific environment  Evolution is common ground shared by all of life sciences and it contributes to our understanding of psychology, neuroscience and behaviour  Distinguish between similar looking bird species o Sanderlings, Semipalmated, and Dunlin Sandpipers  Wing-beat patterns  Flock size  Presence of absence of bi-parental care  Foraging style  Researchers should allow only docile individuals to reproduce in order to study behavioural genetics 1XX3 Psychology Notes 1/9/2013 11:43:00 AM January 21, 2013 – Evolution 2 Module 1 – Introduction to Social Behaviours  Humans and social animals appear to behave altruistically; helping others at a cost to themselves Introduction:  Honey bees: all honey bees in a colony don‟t reproduce (don‟t even have a functioning reproductive system) o They spend all their lives helping raise eggs laid by the queen (bees often die defending their colony)  Belding‟s ground squirrels: frequently give alarm calls to warn others that a predator is near so others can hide; the whistle blower draws attention to itself, alerting predator to its location  Humans: cooperating and helping family, friends and strangers  Selfish gene: evolution acts at the level of genes that contribute to an individual‟s fitness will consequently get replicated more often, increasing frequency in successive generations Types of Social Behaviour  Table of social behaviours o Effect on recipient‟s fitness o Effect on actor‟s fitness  Positive effect of actor‟s well-being + positive effect on recipient‟s well-being = cooperation  Positive effect on actor‟s well-being + negative effect on recipient‟s well-being = selfishness  Negative effect on actor‟s well-being + positive effect on recipient‟s well-being = altruism  Negative effect on actor‟s well-being + negative effect on recipient‟s well-being = spite Cooperation = personal gain  Sports example: teach child how to play better to benefit the team  Pay off to the team: benefit in the long run because team performs better o Increasing fitness of others can sometimes improve your own fitness prospects o Cost of teaching < benefit of being on winning team Module 2 – Group Selection Introduction  The good of the helping gene: group selection o Not for the good of the group, but rather for the good of the gene o The increase in group success translates into better success translates into better success for the metaphorical helping gene Good of the Group?  Example: birds foraging in groups – cooperation where both actor and recipient benefit from an action o More time feeding, less time watching  More competition?  Increased likelihood of finding food: when more individuals are looking for it  The foraging-vigilance trade-off: gives predators the advantage of a surprise attack  Head jerks by individuals vs. by the entire flocks: foragers need to be vigilant as a trade off; head jerks increase as flock size increases o Group as a whole is more vigilant and one by itself  Can selection be good for the group and bad for the gene? (NO) o Everyone benefits in a group setting o Given advance warning of predators The Problem of Altruism  Altruism: behaviour in which the actor incurs a cost to provide a benefit to a recipient  Not altruism: foraging/vigilance in groups; not altruism, because actor gains directly from behaviour  Group of altruists will thrive because individuals in the group are regularity helping each other  An individual who behaves altruistically decreases its own direct fitness  Is foraging/vigilance altruism? o Unless the genes involved in the altruistic behaviour produce more copies of themselves than other genes that don‟t lead to altruism the good of the group cannot explain the evolution of altruism, or any other social behaviour  Example: Lemmings (selfishness vs. altruism) o Lemmings live far North and carry the myth about suicidal population control  Sacrificial act is altruistic because the rest of the lemmings have enough food to survive Module 3 – Inclusive Fitness Introduction  Eusocial hymenoptera: includes all ants, some bees and some wasps; most individuals spend their lives serving the colony without reproducing  Individuals that give up their own reproductive opportunities to help other individuals survive and reproduce seem to epitomize altruism Inclusive Fitness: a measure of an individual‟s reproductive success considering both its own offspring and offspring of relatives  Genes for altruism could be successful if they helped identical copies of themselves  Direct Fitness: copies of an individual‟s genes are passed on to the next generation via offspring o Fitness from personal reproduction o You can increase your fitness by helping kin to successfully raise their offspring, sometimes even when doing so has negative effects on your won direct fitness  Indirect Fitness: copies of an individual‟s genes are passed on to the next generation via the offspring of relatives o Fitness from the reproduction of close genetic relatives o Natural selection can favour not only behaviours that increase an individual‟s own reproductive success but also behaviours that increase the reproductive success of close genetic kin  Shared genes between relatives can drive the evolution of altruism  Direct fitness + indirect fitness = inclusive fitness o An individual‟s fitness is measured by the # of copies of its genes left in the next generation  W.D. Hamilton: he was troubled in 1960‟s by evolution of altruism because standard accounts of natural selection could never favour genes for self-sacrifice o The solution was as simple as recognizing that genes for altruism could be successful if they helped identical copies of themselves Hamilton‟s Rule – the reproductive benefit to the recipients (B) multiplied by the probability that the recipients actually have identical copies of the same gene, or coefficient of relatedness (r), must be greater than the reproductive cost to the actor (c)  rB>c  Inequality that predicts when altruistic behaviour will be favoured  C
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