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Chapter 2

Chapter 2 - Evolution Video Lecture Psych 1XX3

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Joe Kim

Video Lecture Psych 1XX3 Chapter 2: Evolutionary Psychology Evolution 1  Biological sciences goal – to elucidate the adaptive designs of living things  Interested o Adaptations: the working parts – the functional systems and subsystems – that animals are made up of Adaptations  Adaptations – biological traits/characteristics that help an individual to survive and reproduce in its habitat; perform a specific function o Always “for” something, they perform specific functions that make an organism better suited to its environment  Biological traits aren’t simply morphological – perceptual processes and behaviors are also biological adaptations  Adaptationists – scientists use this label to describe how hypotheses about adaptive function guide their investigations  “Higher” Mental Processes – tasks that the mind needs to accomplish to do its job; refer to adaptive functions of mental activity o Selective attention o Memory encoding o Memory Retrieval o Word Recognition  Cognitive Psychologists are Adaptationists – they find it helpful to analyze their subject matter into adaptive problems or tasks, and to look for the adaptations that solve those problems  Adaptive functions that are served by our minds evolved like all other adaptations through natural selection Evolution by Natural Selection  Adaptations emerge in development as a result of the activation of relevant genes in interaction with relevant aspects of the environment  Natural Selection – the differential survival and reproduction of organisms as a result of heritable differences between them o Three Essential Components 1. Individual Differences – within any population, there is variation among individuals chances of surviving and reproducing 2. Differential Reproduction – some individuals will have more offspring than others 3. Heritability – the offspring of successful reproducers will resemble their parents with respect to these variable characteristics o Discovered by Charles Darwin and Alfred Russell Wallace o One of the 4 basic mechanisms of evolution (others being mutation, genetic drift and migration)  Selective Transmission – specific characteristics that are best adapted for survival and reproduction are going to be reproduced at higher rates Natural Selection in the Wild  Stabilizing Selection – selection against any sort of departure from the species – typical adaptive design o Tends to keep traits stable over generations  In situations when there’s been a significant change in the environment, selection favors traits that are not typical and evolutionary change can be observed  (Galapagos) Daphne Island Medium Ground-Finches Video Lecture Psych 1XX3 o Peter and Rosemary Grant studied this birds and were able to observe natural selection within a generation o 1977 – a severe drought decimated the vegetation; only large, tough seeds that the finches usually didn’t bother with were left  Birds with unusually heavy beaks were able to eat the hard seeds and were able to survive the drought; as opposed to the small beaked birds who died of starvation o From 1976 to 1978 – the average beak depth increased from 9.4 mm to 10.2 mm  The large-beaked survivors went on to reproduce when the conditions were again favorable for breeding – beak size is heritable o When drought ended, smaller seeds were again abundant and the average beak depth returned to the pre-drought sizes Reproductive Success = Fitness  Darwinian Fitness – average reproductive success of a genotype relative to alternative genotypes  Evolution – a change in gene frequencies over generations  Sexual Selection – the component of natural selection that acts on traits that influence an organisms ability to obtain a mate o Competition for mates; natural selection acts on mate-finding and reproductive behaviors o Peacock’s Tail  Energetically expensive to produce  More conspicuous to predators  Harder to get away from predators  Increases risk of dying  Fitness is a matter of reproduction, not necessarily survival  Selective force in evolution of tail was the female’s choice o Elks Antlers  Used for competing for dominance status  Winner monopolizes a harem of females  Bulky – more difficult to evade predators  Selective force was the success in combat with other males o The component of natural selection (the differential reproduction of types) that results from differential access to mates 1. Being chosen by the opposite sex 2. Defeating same sex rivals in mating competition o Hint that it is a sexually selected trait if o If an anatomical trait differs between the sexes o If the sex difference only exists in the breeding season or is exaggerated at that time of year Species-Typical Behavior & Comparative Approach  Behaviors are evolved, species specific adaptions  Test hypotheses about adaptive functions  Sandpiper o Different types; can differentiate by observing behavior, vocalizations, dietary and habitat preferences and their signature way of foraging  Dunlin – like muddier shores  Semi-palmated – like muddier shores  Sanderling – like sandier beaches, flocks race out after receding waves an furiously peck at tiny insects on the wet sand then race back towards the shore in front of the next wave  Behavior Genetics Experiments o Can keep animals in captivity and selectively breed those with specific traits and you can change the animals typical behavior in a few generations o Fruit Fly, Drosophila – popular animal in experiments because they have short generation times Video Lecture Psych 1XX3 Evolution II Social Behaviors  Organisms evolved to maximize their fitness and reproductive success – although there are situations where individuals appear to behave altruistically (helping others at a cost to themselves) o Honey Bees  Virtually all honey bees in a colony don’t ever reproduce – they don’t even have functioning reproductive organs  Instead of reproducing themselves, they spend their lives in the service of the colony helping to raise eggs laud by the Queen and many bees often die defending their colony from predators o Belding’s Ground Squirrels  Individuals will frequently give alarms calls to warn others that there is a predator in the area, giving everyone a change to flee and hide  But by giving an alarm call, the “whistle blower” draws attention to itself, alerting the predator to its exact location o Humans  Selfish Genes – that natural selection will favor the genes and gene complexes that best serve their own interest, namely replication  Four types of social behavior that individuals engage in o Cooperation o Selfishness o Altruism o Spite  Cooperation = personal gain o Assume: Cost of teaching < Benefit of being on a winning team  Increasing the fitness of others can sometimes improve y
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