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The Development of Evolutionary Theory

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PSYC 2520
Hernan Humana

Chapter 3: The Development of Evolutionary Theory Biological evolution changes that take place in genetic and physical chracteristics of a population or group of organisms over time Adaptive significance effectiveness of behaviour in aiding organisms to adjust to changing environmental conditions psychologists research how past environmental conditions favoured certain behaviour and how immediate envornment influences choices interested in ultimate causes of behaviour and proximate causes ultimate causes evolutionary conditions that have slowly shaped behaviour of species over generations proximate causes - immediate environmental events and conditions that affect behaviour Clark and Galef different behaviour of male gerbils next to other male or female in utero traced to presence or absense of testosterone during gestational periods evolutionary reason? Clark, Desousa, Vonk, and Galef examined subsequent behaviours of male gerbils who were gestated next to females: when they did mate successfully gerbils were good fathers spent time in contact with pups, and mates became sexually active more quickly (mating stratefy better performers or parents) by understanding adaptive behaviour developed through long-term process of evolution, psychologists are able to gain better understanding of our abilities to adjust to changes in immediate environment members of human species (ultimate cause) and have learned to act in certain ways (proximate cause) evolutionary psychology studies ways which organism's evolutionary history contributes to development of behavioural patternsa nd cognitive strategies related to reproduction and survivial during lifespan culture sum of socially transmitted knowledhe, customs, and behaviour patterns common to particular group of people British naturalist Alfred Russel Wallace also devised theory natural selection same time as Darwin Voyage of the Beagle Christ's College degree in Theolody met captain Fitz Roy in 1831 unpaid naturalist companion on Beagle, ten-gun brig converted to ocean research vessel that ended in 1836 mission was to explore and survey coast of SA and to make hydographic measurements worldwide almost rejected bc of shape of nose (couldnt possess needed energy and determination) Darwin observed flora and fauna of South America, South Africa, and islands of Pacific, South Atlantic, and Indian oceans, including Galapagos collected creatures and objects and sent them back to England to be studied by naturalists of Europe naturalism ascribed doctrine of essentialism, dating back to Plato that all living things belong to fixed class or kind, defined by an essence that characterizes it alone didnt come up with theory of evolution until after trip The Origin of Species compared similarities and differences in creatures he had found adn carefully reviewed work of earlier naturalists, including grandfather, who had specualted about concept of evolution but were unable to propose believable process by which it occured became interested in artificial selection and bred pigeons for a while artificial selection procedure in which animals are deliberately mated to produce offspring that possess particularly desirable characteristics natural selection concequence of fact that, because there are physical and behavioural differences among organisms, they reproduce differently; within a given population, some animals the survivors - will produce more offspring than other animals came to this realization in September 1838 but did not publish until 20 years later because wanted supportive evidence Wallace sent his theory to Darwin, which he developed during a bout of fever in Spice Islands after reading Mathalus population presented theory together to Linnean Society and Darwin published the Origin of Species a year later Natural Selection and Evolution Mayr suggested that Darwin's immense contributions to modern thinking about evolution can be traced to four insights: species are not fixed but rather change over time; evolution is branching process, implying that all species descend from single common ancestor; that evolution is continuous, with gradual changes; and that evolution is based on natural selection Natural Selection based on two premises: individuals within population show variability in heritable behavioural and physical characteristics capacity of environment to sustain a population of any species is limited, producing competition behavioural adaptations were especially important to survival and therefore an important part of evolution reproductive success number of viable offspring an individual produces relative to number of offspring produced by members of same species; evolutionary bottom line Variation variation differences found across individuals of any given species in terms of their genetic, biological (size, strength, physiology) and psychological (intelligence, sociability, behaviour) chracteristics caused by individual's gentic makeup (genotype) and as a result physical chracteristics and behaviour (phenotype outward expression of organism's genotype; physical appearance and behaviour) vary phenotype is produced by interaction between genotype and enviornment - genotype determines how much environment can influence organism's development and behaviour Peter and Rosemary Grant studied finches and noticed that amount ofrainfall and size of food supply directly affected mortality of finches having certain types of beaks (drought - small seeds scarce so small beaked birds die) made two important points: although evolution occurs over long run, natural selection can produce important changes in short run only a few years phenotypic variation can produce important selective advantages that affect survival Competition competition striving or vying with others who share same ecological niche for food, mate and territory Rele, Mcdam, Boutin, and Berteaux found that average time at which female squirrels gave birth advanced more than two weels in just ten years coinciding with increased amount of pinecones stored in trees found that each new generation produced a birthdate that was about one day earlier than that of previous generation can use correlation methods Natural Selection in Human Evolution early hominid Ardipothecus ramidus lived about 4.4 million years ago in Africa later creatures Australopithecus anamensis and Australopithecus afarensis were clearly similar and bipedal viewpoint supported from statistical evidence is that over oeriod from 3-2 million years ago homonid line split in 2 African environment turned drier, altering sources of food one line evolved into genus wit
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