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Psych- Evolution.pdf

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Department
Psychology
Course
PSYCH 1XX3
Professor
Joe Kim
Semester
Winter

Description
Critical Period Research - Differences in brain structure were observed in rats raised in either enriched or deprived environments Implications Of Critical Periods - Likely to affect parental decisions o Can lead parents to over-stimulate their children before they are even born - Could affect decisions to adopt o Can lead people to not adopt older children - Affects public policy on child intervention Experience-expectant Brain Growth:Brain has evolved to expect a certain amount of environmental input and with this input it can develop normally. Experience-dependent Brain Growth:Brain develops according to personal experiences. Sensitive Periods - Replaced the term critical period - Brain maintains some residual capacity for change and growth in adulthood - Flexibility in the timing and type of stimulation required for normal development Evolution I Adaptation: Biological traits (characteristics) that help an individual survive and reproduce in its habitat. - Perform a specific function that makes an organism better suited to its environment - Ex. Human eyes, raccoons’ paws, bat’s echolocation systems Adaptationists - Biological adaptions include perceptual processes and behaviours - Look for relevant adaptations Higher Mental Processes - Selective attention - Memory encoding - Memory retrieval - Word recognition Evolution By Natural Selection - Natural Selection: Differential survival and reproduction of organisms as a result of heritable differences between them. o Discovered by Charles Darwin and Alfred Wallace - [1] Individual Differences - Within any population there’s variation among individuals for any given characteristic - [2] Differential Reproduction - Caused by differences affecting individual’s chance of survival and reproduction - Some individuals will have offspring than others - [3] Heritability - Heritable traits are passed to offspring - Offspring of successful reproducers will resemble their parents Selective Transmission - From above: [1] + [2] + [3] Î Î Selective Transmission - Ex. A school of red and blue fish - [1] Red fish are red, blue fish are blue - [2] Blue fish camouflage in the ocean and are less visible to predators - Red fish are more visible to predators and get eaten more often - On average, blue fish survive and reproduce better than red fish - [3] Blue fish produces blue-coloured offspring - Over many generations, there’ll be selective transmission of heritable parental traits and the population will be mostly blue - The specific traits that are best adapted for survival/reproduction are going to be reproduced at higher rates Stabilization Selection - Selection against any sort of departure from the species-typical adaptive design - However, sometimes significant environmental change causes selection to favour traits that aren’t typical - Ex. Darwin’s finches - Finches normally eat small seeds - Drought Æ Food became scarce Æ Small seeds quickly eaten Æ Large, tough seeds remained - Birds with large beaks continued to survive - Birds with small beaks died from starvation - 1976 – 1978: Average beak depth increased from 9.4mm – 10.2mm - Beak size is inheritable Æ Offspring inherited large beaks Survival Of The Fittest - Fitness refers to reproductive success (in evolutionary biology) - Natural selection favours those who are best at producing offspring - Darwinian Fitness: Average reproductive success of a genotype relative to alternative genotypes. - Fitness is used to describe how good a particular genotype is at leaving copies of its genes in the next generation relative to other genotypes - Evolution:Changes in allele frequencies over time. Sexual Selection:The component of natural selection that acts on traits that influences an organism’s ability to obtain a mate. - [1] Being chosen by the opposite sex - Ex. Peacock’s tail (a sexually selected trait; only in males) - Trait: Display feature - Effect on survival: Negative - Effect on fitness: Positive - Selective Force: Female choice - Useless with respect to physical survival o Energetically expensive to produce o Increases risk of dying (conspicuous to predators and heavy to carry) - Useful with respect to mating o Tail is attractive to females - [2] Defeating same-sex rivals in mating competition - Ex. Elk’s antlers (a sexually selected trait; only in males) - Trait: Weapon - Effect on survival: Negative - Effect on fitness: Positive - Selective Force: Success incombat - Useless with respect to physical survival o Decreases speed and stamina, thus vulnerable to predators o More likely to get stuck indeep snow - Useful with respect to mating o Used in combat with other elks when competing for mate - In general, if anatomical trait differs between sexes Æ hints a sexually selected trait Mechanisms Of Evolution - Natural Selection - Mutation - Genetic Drift - Sexual Selection - Migration (Genetic Flow) Species-Typical Behaviour - Behaviours are evolved, species specific adaptations - Includes topography (physical form), habitat preference, and group size - Behaviour genetics experiments can be performed to test if behavi
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