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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 of rainfall 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 with powerful jaws that could crush and chew plants and nuts – Paranthropus and other line continued to form Australopithicus that formed two distinct species 2.5-1.8 million years ago – Homo rudolfensis and Homo habilis (handy man – originator of stone tools) ● Hominids has encepholization – increased brain size, requires more calories, tools an advantage ● disputed way it altered hominid life – either associated with specific home base used by groups to share food and raise children or carried with them to help scavenge meals ● hominids left african home 1.8 million years ago used stone chipped tool – homo erectus found as far as in Java and China ● 600,000 years ago Homo heidelbergensis prepared very planned tools – single directed blow would detach finished tool  sapiens and neanderthalensis evolved from that species  originated in Africa 150000-200000 years ago ● success stems from bipedalism and ecephelization ● Dunbar – suggests that homo sapiens evolved in environment that favoured large groups  large groups can remain together only if they can remember small nuances that underlie social interactions  correlation between primates with encephalization and large groups  humans can naturally function in group of 148 ● memorizing and recalling actions evovled first, then language and capacity to manipulate symbols ● planning – capacity to anticipate future events and to take into account effects that those events might have on individual or group of individuals – organization of hunts, institution of social customs and events, planting and harvesting crops ● Skinner – language provided not only simple means of warning others of danger, but also means of communicatinf important information to others and ability to reinforce social bonds (conversation replaced grooming) ● neaderthal didnt develp much cultural traditions – sapiens advantage ● agriculture revolution 10 000 years ago, industrial revolution 150 years ago, and technological revolution 50 years ago (transistor, integrated circuit, computer) ● Cultural evolution - adaptive changes of cultures in response to environmental changes over time; only possible because humans have been gentically endowed with capacity for learning and language ● Marvin Harris – capacity for learning evolved because it leads to more flexible and rapid method of achieving reproductive succes and it allows entire groups of people to adjust or take advantage of novel opportunities in a single generation without having to wait for appearance and spread of genetic mutations Summary ● ultimate causes – historical events and conditions in evolution of species that have shaped its behaviour ● proximate causes – how animals adapt to environmental changes through learning Heredity and Genetics ● genetics – study of genetic makeup of organisms and how it influences thier physical and behavioural characteristics; study of structure and function of genes, how they are transmitted from one generation to another, and how they operate in populations ● Heredity – sum of traits and tendencies inherited from a person's parents adn other biological ancestors ● Darwin could not explain inheritance ● Gregor Mendel, an Australian Monk, uncovered basis of genetics 6 years after Origin of Species Basic Principles of Genetics ● DNA (deoxyribonucleic acid) – strands of sugar and phosphates are connected by rungs made from nucleotide molecules adenine, thymine, guanine, and cytosine; discovered by James Watson and Francis Crick ● Gene – location of particular sequence of nucleotides along DNA molecule; some may contain short sequence of nucleotides while others contain millions; direct synthesis of protein and enzymes ● Genome – total set of genetic material of an organism; 24 different DNA molecules in women and 25 in men; 30 000 – 40 000 genes in human genome, only twice number in housefly or worm Genes as recipes for Protein Synthesis ● Genes influence physical and behavioural development through protein synthesis – combining proteins necessary to create and develop physiological structures and for behaviour (how structures might function in response to environmental stimulation ● proteins are strings of amino acids arranged in chain whose order is specified by nucleotides adenine, thymine, guanine, and cytosine ● no genes for behaviour – only physical structures and physiological processes related to behaviour  novelty seeking is associated with high levels of dopamine ● genes also direct synthesis of enzymes – proteins that regulate structure of bodily cells and processes occurring within those cells; controls each cell’s structure and function Chromosomes and Meiosis ● chromosomes – rod-like structures in nuclei of living cells; contain genes although small percentage of genes is located in DNA within cell’s mitochondria  each set contains different DNA molecule and therefore different sequence of genes rd  inherit 23 pairs (46 total), 22 matching (autosomes) and 23 is sex chromosome ● reproduction involves union of sperm, and egg – differ from other cells:  have only one member of each chromosomes pair  some of genetic information on one member of pair has been exchanged with information on other member ■ produced by meiosis – form of cell division where chromosomes within cell are randomly rearranged so that new sperm and ova contain 23 individual chromosomes ■ can produce 2^23 (8388608) different ova and sperm Dominant and Recessive Traits ● each pair of chromosomes contains pairs of genes
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