chapter-2-notes-summary-biopsychology.pdf

lOMoARcPSD|30327462 Chapter 2 Notes - Summary Biopsychology Introduction to Neuroscience (Baylor University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Do...

lOMoARcPSD|30327462 Chapter 2 Notes - Summary Biopsychology Introduction to Neuroscience (Baylor University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 1 Chapter 2 – Evolution, Genetics, and Experience I. Thinking about the Biology of Behavior: From Dichotomies to Interactions a. The Origins of Dichotomous Thinking i. IS IT PHYSIOLOGICAL, OR IS IT PSYCHOLOGICAL? 1. René Descartes (1596–1650): argued that universe is composed of 2 elements: a. Physical Matter (behaves according to laws of nature & suitable object of scientific investigation–human body (including brain) & nonhuman animals) b. Human Mind (lacks physical substance, controls human behavior, obeys no natural laws–soul, self, or spirit) A.KA. Cartesian Dualism ii. IS IT INHERITED, OR IS IT LEARNED? 1. A.K.A. Nature–Nurture Issue 2. Ethology: Study of animal behavior in the wild 3. European ethology focused on study of instinctive behaviors, emphasizing the role of nature, or inherited factors in behavioral development. 4. North America: Experimental psychology b. Problems with Thinking about the Biology of Behavior in Terms of Traditional Dichotomies i. PHYSIOLOGICAL–OR –PSYCHOLOGICAL THINKING RUNS INTO DIFFICULTY 1. 2 lines of evidence against physiological–or –psychological thinking a. 1. Composed of many demonstrations that even most complex psychological changes can be produced by damage to, or stimulation of parts of brain. (Ex. Patient suffering from asomatognosia–unaware of certain parts of one’s own body due to damage in right parietal lobe) b. 2. Composed of demonstrations that some nonhuman species, particularly primate species, possess some abilities that were once assumed to be purely psychological thus purely human. (Ex. Chimps w/ Mirrors) ii. NATURE–OR–NURTURE THINKING RUNS INTO DIFFICULTY 1. Factors other than genetics & learning were shown to influence behavioral development, such as fetal environment, nutrition, stress, & sensory stimulation 2. Changed nature – or – nurture dichotomy from “genetic factors or learning” to “genetic factors or experience” 3. Argued that behavior always develops under combined control of nature & nurture a. How much is nature & how much is nurture? i. Flawed bc it’s based on premise that genetic factors & experimental factors combine in additive fashion iii. A MODEL OF THE BIOLOGY OF BEHAVIOR 1. All behavior is product of interactions among 3 factors: a. 1. Organism’s genetic endowment, product of evolution b. 2. Its experience c. 3. Perception of current situation II. Human Evolution a. Darwin’s Theory of Evolution i. On the Origin of Species in 1859 explained his theory of evolution ii. Wasn’t the 1st to suggest that species evolve from preexisting species, but was 1st to amass large body of supporting evidence & 1st to suggest how evolution occurs iii. Presented 3 kinds of evidence to support his assertion: Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 2 1. 1. Documented the evolution of fossil records through progressively more recent geological layers. 2. 2. Described striking structural similarities among living species, suggesting that they had evolved from common ancestors. 3. 3. Pointed to major changed that had been brought about in domestic plants & animals by selective breeding iv. Argued that evolution occurs through natural selection 1. Selectively breeding the fittest. 2. Fitness: ability of organism to survive & contribute its genes to next generation b. Evolution & Behavior i. SOCIAL DOMINANCE 1. Males of many species establish a stable hierarchy of social dominance through combative encounters w/ other males 2. Why is social dominance important factor in evolution? a. Some species, dominant males copulate more than nondominant males & thus are more effective in passing on their characteristics to future generations b. Some species, dominant females are more likely to produce more & healthier offspring ii. COURTSHIP DISPLAY 1. Thought to promote the evolution of new species 2. Species: Group of organisms reproductively isolated from other organisms; members of species can produce fertile offspring only by mating w/ members of same species 3. Conspecifics: Members of same species c. Course of Human Evolution i. EVOLUTION OF VERTEBRATES 1. Complex multicellular water–dwelling organisms, 1st appeared on earth about 600 mil yrs ago. 2. About 150 mil yrs later, 1st chordates (animals w/ dorsal nerve cords) evolved 3. 1st chordates w/ spinal bones to protect their dorsal nerve cords evolved 25 mil yrs later 4. 1st vertebrates were primitive bony fishes 5. Today, 7 classes of vertebrates: 3 classes of fishes, + amphibians, reptiles, birds, & mammals 6. Vertebrae: Spinal bones 7. Vertebrates: Chordates that possess them ii. EVOLUTION OF AMPHIBIANS 1. About 410 mi years, 1st bony fishes started to venture out of the water 2. Fishes that could survive on land for brief periods of time had 2 great advantages: 1. Could escape from stagnant pools to nearby fresh water 2. Could take advantage of terrestrial food sources 3. 1st amphibians evolved about 400 million yrs ago iii. EVOLUTION OF REPTILES 1. About 300 mil yrs ago reptiles evolved from branch of amphibians 2. 1st vertebrates to lay shell-covered eggs & be covered by dry scales a. Reduced reliance of reptiles on watery habitats iv. EVOLUTION OF MAMMALS 1. About 180 mil yrs ago, evolved from 1 line of small reptiles Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 3 2. Females fed their young w/ secretions from mammary glands (named mammals bc of this gland) 3. Eventually mammals stopped laying eggs, instead young were nurtured in watery environment of their bodies until young were mature enough to be born a. Proved to have considerable survival value, provided long-term security & environmental stability necessary for complex programs of development to unfold b. Humans: primates (Latin: primus, “1st” or “foremost” v. EMERGENCE OF HUMANKIND 1. Primates of tribe that includes humans are Hominini a. Tribe composed of at least 6 genera: i. Australopithecus ii. Paranthropus iii. Sahelanthropus iv. Orrorin v. Pan vi. Homo b. Homo is thought to be composed of at least 8 species, 7 of those species are extinct whereas Homo sapiens are not c. 3 important hominin fossil recent discoveries made: i. 1. Uncommonly complete fossil of 3 yr old early Australopithecus girl in Ethiopia. ii. 2. Fossils indicating a population of tiny hominins inhabited Indonesian island of Flores as recent as 18,000 yrs ago. iii. 3. Several early Australopithecine fossils w/ combinations of human & nonhuman characteristics in a pit in South Africa 2. Australopithecines evolved about 4 mil yrs ago in Africa a. Only about 1.3 m (4 ft) tall & had small brains b. Analysis of pelvis & leg bones indicate their posture was upright 3. 1st Homo species thought to have evolved from 1 species of Autralopithecus about 2–2.8 mil yrs ago a. 1 distinctive feature: large size of their brain cavity (larger than Australopithecus but smaller than modern humans) b. Used fire & tools & coexisted in Africa w/ various species of Australopithecus about ½ mil years, until Australopithecines died out 4. Big 3 human attributes: a. 1. Large brain b. 2. Upright posture c. 3. Free hands w/ opposable thumb d. Thinking about Human Evolution i. Commonly misunderstood point about evolution 1. Evolution does not proceed in a single line 2. Humans have little reason to claim evolutionary supremacy. Last surviving species of a family that has existed for only a blip of evolutionary time 3. Evolution doesn’t always proceed slowly & gradually 4. Few products of evolution have survived to present day–only tips of branches of evolutionary bush have survived 5. Evolution doesn’t progress to preordained perfection 6. Not all existing behaviors or structures are adaptive Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 4 a. Spandrels: Incidental nonadaptive evolutionary by-products (ex. Bely button) 7. Not all existing adaptive characteristics evolved to perform current function a. Exaptation: Evolved to serve 1 function & later co-opted to serve another 8. Similarities b/w species don’t necessarily mean that species have common evolutionary origins a. Homologous: Structures that are similar bc they have a common evolutionary origin b. Analogous: Structures that are similar but do not have common evolutionary origin c. Convergent Evolution: Evolution unrelated species of similar solutions to same environmental demands 9. Now considerable evidence that Homo sapiens mated w/ other Homo species they encountered w/in Africa & as they migrated out e. Evolution of the Human Brain i. Early research assumed that brain size & intellectual capacity were closely related 1. 2 problems: a. 1. Modern humans do not have the biggest brains. b. 2. Sizes of brains acclaimed intellectuals were found to be unremarkable. 2. Brain weight expressed as % of total body weight might be better measure of intellectual capacity 3. More reasonable approach to study brain evolution is to compare evolution of diff brain regions 4. 3 important pts of about evolution of human brain: a. 1. Brain has increased in size during evolution. b. 2. Most of increase in size occurred in cerebrum. c. 3. Increase in # of convolutions has greatly increased the surface area of cerebral cortex f. Evolutionary Psychology: Understanding Mate Bonding i. In most vertebrate species, mating is totally promiscuous 1. Promiscuity: mating arrangement in which members of both sexes indiscriminately copulate w/ many diff partners during each mating period 2. Mating bonds: enduring mating relationships ii. POLYGYNY & POLYANDRY 1. Polygyny: Arrangement in which 1 male forms mating bonds w/ more than 1 female 2. Polyandry: Mating arrangement in which 1 female forms mating bonds w/ more than 1 male iii. MONOGAMY 1. 9% mammalian species are primarily monogamous 2. Monogamy: mate-bonding pattern in which enduring bonds are formed b/w 1 male and 1 female iv. THINKING ABOUT EVOLUTIONARY PSYCHOLOGY 1. Evolutionary theory of mate bonding has led to several predictions about current aspects of human mate selection: a. Men in most cultures value youth & attractiveness in their mates, Women value power & earning capacity b. Physical attractiveness best predicts which women will bond w/ men of high occupational status Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 5 c. Major–mate-attraction strategy of women is increasing their physical attractiveness, men is displaying their power & resources d. Men are more likely than women to commit adultery III. Fundamental Genetics a. Mendelian Genetics i. Decided to study dichotomous traits & decided to begin his experiments by crossing the offspring of true-breeding lines 1. Dichotomous Traits: Occur in 1 form or another, never in combination 2. True-Breeding Lines: Breeding line in which interbred members always produce offspring w/ same trait, generation after generation ii. Dominant Trait: Appears in all of 1st gen offspring iii. Recessive Trait: Appears in ¼ of 2nd gen offspring iv. Phenotype: Observable traits v. Genotype: Traits that can pass on to its offspring through genetic material vi. Devised theory to explain his results: 1. 2 kinds of inherited factors for each dichotomous trait a. Gene: Each inherited factor 2. Each organism possesses 2 genes for each of its dichotomous traits a. Alleles: 2 genes that control same trait b. Homozygous: 2 identical genes for a trait c. Heterozygous: 2 diff genes for a trait 3. 1 of 2 kinds of genes for each dichotomous trait dominates the other in heterozygous organisms 4. Each dichotomous trait, each organism randomly inherits 1 of its “father’s” 2 factors & 1 of its “mother’s” 2 factors b. Chromosomes i. REPRODUCTION & RECOMBINATION 1. Early 20th century found that genes were located on chromosomes a. Occur in matched pairs, each has a characteristic # of pairs in each of its body cells 2. Meiosis: process of cell division that produces gametes a. Chromosomes divide, & 1 chromosome of each pair goes to each of 2 gametes that results from cell division i. Each gamete only has ½ of usual # of chromosomes st b. 1 stage: Chromosomes line up in their pairs, then members of each pair cross over one another @ random points, break apart @ points of contact, & exchange sections (Genetic recombination) 3. Mitosis: All other cell division in body a. # of chromosomes doubles so that, when cell divides, both daughter cells end up w/ full complement of chromosomes ii. STRUCTURE & REPLICATION 1. DNA: double-stranded molecule a. Each strand is sequence of nucleotide bases 4 bases: i. Adenine ii. Thymine iii. Guanine iv. Cytosine b. Sequence of bases on each chromosome that constitutes genetic code 2. Replication: Critical process of DNA molecule a. w/o it mitotic cell division wouldn’t be possible Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 6 b. Mutations: accidental alterations in individual genes iii. SEX CHROMOSOMES & SEX-LINKED TRAITS 1. Autosomal chromosomes: Matched pairs a. Exception is sex chromosomes 2. Sex-linked traits: Traits influenced by genes on sex chromosome 3. Dominant traits occur more frequently in females 4. Recessive traits occur more frequently in males c. Genetic Code & Gene Expression i. Proteins: Long chains of amino acids 1. Control physiological activities of cells & important components of cellular structure 2. Diff kinds of cells develop bc of the stretches of DNA that lack structural genes ii. Enhancers: Stretches of DNA whose function is to determine whether particular structural genes initiate synthesis of proteins & @ what rate 1. Can be regulated in 2 ways: Can be turned up or down iii. Gene Expression: Production of protein specific by particular gene iv. Transcription factors: proteins that bind to DNA & influence extent to which genes are expressed v. Expression of structural gene: 1. Small section of chromosome that contains gene unravels & unraveled section of 1 of DNA strands serves ad template for transcription of short strand of RNA. 2. Once left the nucleus, messenger RNA attaches itself to one of many ribosomes in cell’s cytoplasm 3. Ribosome moves along strand of messenger RNA, translating genetic code as it proceeds vi. Messenger RNA: strand of transcribed RNA vii. Codon: each group of 3 consecutive nucleotide bases along messenger RNA stand 1. Instructs ribosome to add 1 of 20 diff kinds of amino acids to protein it’s constructing 2. As ribosome reads codon, attracts a transfer RNA molecule that is attached to appropriate amino acid 3. Ribosome reads codon after codon that tells it the protein is complete, completed protein is released into cytoplasm viii. Transfer RNA: molecules of RNA that carry amino acids to ribosomes during protein synthesis ix. Gene expression involves 2 phases: 1. Transcription of DNA base-sequence code to RNA base-sequence code 2. Translation of RNA base-sequence code into sequence of amino acids d. Human Genome Project i. Purpose of collab was to compile a map of sequence of all 3 billion bases that compose human chromosomes ii. Motivated by potential medical applications 1. Assumed that once human genome was described, it would be a relatively straightforward matter to link variations in the genome particular to human disease & then develop treatment & prevention programs tailored to individual patients. iii. Has changed our understanding of ourselves & revolutionized the field of genetics iv. 3 major contributions of Human Genome Project: 1. Many new techniques for studying DNA were developed 2. Humans have relatively few genes surprised many scholars Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 7 a. Human Proteome: Complete map of entire set of proteins encoded for by our genes 3. Many variations in human genome related to particular diseases have been identified e. Modern Genetics: Growth of Epigenetics i. Interest shifted away from protein-encoding genes & their expression to other possible mechanisms of inheritance ii. Interest shifted to mechanisms by which experience exerts its effects on development iii. Epigenetics: Study of all mechanisms of inheritance other than genetic code & its expression iv. Why did epigenetics rise to prominence so quickly @ turn of century? 1. Human Genome Project had just discovered that genes constitute only about 1% of human DNA 2. 1990s vast majority of RNA molecules were found to be small – only 1.2% were of large protein – encoding variety. Indicated that protein encoding is only a minor function of RNA. 3. For decades there had been a general consensus that inheritance was product of gene-experience interactions & yet mechanisms by which critical interactions took place were unknown 4. At turn of century, there was newly available arsenal of research techniques resulting from Human Genome Project v. 5 important advances in epigenetics: 1. Epigenetic investigations of nongene DNA have identified many active areas 2. Small RNA molecules have found to come in a variety of diff types 3. Many epigenetic mechanisms have been discovered by which gene expression can be regulated, 2 of most widely studied are DNA methylation & histone remodeling a. DNA methylation: Reaction that occurs when methyl group attaches to DNA molecule, usually @ cytosine sites in mammals b. Histone remodeling: Reaction that occurs when histones change their shape & in so doing influence shape of adjacent DNA c. Histones: proteins around which DNA is coiled 4. Some epigenetic effects regulate gene expression by acting on messenger RNA rather than genes, called RNA editing 5. Epigenetic changes such as DNA methylation & histone remodeling can be induced by particular experiences that can last a lifetime vi. Transgenerational Epigenetics: Subfield of epigenetics that examines the transmission of experience via epigenetic mechanisms across generations IV. Epigenetics of Behavioral Development: Interaction of Genetic Factors & Experience a. Ontogeny: Development of individuals over their life span b. Phylogeny: Evolutionary development of species through ages c. Selective Breeding of “Maze–Bright” & “Maze–Dull” Rats i. Tyron focused his selective-breeding experiments on behavior that had been focus of early psychologists in investigations of learning 1. Began by training a large heterogeneous group of laboratory rats to run a complex maze a. Paired Maze-bright: 2 smart rats who solved maze b. Paired Maze-dull: 2 dumb rats who didn’t solve maze c. Used cross-fostering control procedure Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 8 2. Any measurable behavioral trait that varies among members of a species can be selectively bred 3. Selective-breeding studies have proved that genes influence the development of behavior d. Phenylketonuria: A Single-Gene Metabolic Disorder i. Phenylketonuria: High levels of phenylpyruvic acid in urine 1. Discovered in 1934 2. Behavioral symptoms result from interaction b/w genetic & environmental factors b/w PKU gene & diet 3. Sensitive period: Period during which particular experience must occur to have major effect on development of trait e. Development of Birdsong i. Studies of ontogenetic development of birdsong suggest that this behavior develops in 2 phases: 1. Sensory phase: begins several days after hatching 2. Sensorimotor phase: begins when juvenile males begin to twitter subsongs (immature songs of young birds), usually when several months old ii. Canary song neural circuit is remarkable in 3 respects: 1. Left descending motor pathway plays a more important role in singing than the right descending motor pathway 2. High vocal center is 4x larger in males than females 3. Each spring, males song-control structure of its brain double in size, only to shrink back in the fall V. Genetics of Human Psychological Differences a. Development of Individuals vs Development of Differences among Individuals i. Often compare monozygotic twins w/ dizygotic twins ii. Studies of pairs of monozygotic & dizygotic twins who’ve been separated @ infancy by adoption are informative about relative contributions of genetics & experience to diffs in human psychological development b. Heritability Estimates: Minnesota Study of Twins Reared Apart i. 59 pairs of monozygotic twins & 47 pairs of dizygotic twins who had been reared apart ii. Each twin was brought to University of Minnesota, tested for approx. 50 hrs (focused on intelligence & personality) iii. Heritability estimate: numerical estimate of the proportion of variability that occurred in particular trait in particular study as result of genetic variation in that study 1. Tells us about contribution of genetic diffs to phenotypic diffs among participants in a study c. A Look into the Future: Two kinds of Twin Studies i. TWIN STUDIES OF EPIGENETIC EFFECTS 1. @ conception monozygotic twins are genetically identical, & by repeatedly assessing their DNA one can document the development & survival of many epigenetic diffs that develop b/w them 2. 1st systematic demonstration of epigenetic diffs in human twins was published by Fraga & colleagues a. Took tissue samples from 40 pairs of monozygotic twins ranging from 3- 74 yrs old 3. Wong & colleagues a. Examined DNA methylation in buccal cells b. Concluded that diffs in DNA methylation are mainly consequence of experiential factors Downloaded by Micah Clado ([email protected])  lOMoARcPSD|30327462 9 ii. TWIN STUDIES OF THE EFFECTS OF EXPERIENCE ON HERITABILITY 1. Heritability estimates for intelligence tended to be about 75% 2. Turkheimer & colleagues assessed heritability of intelligence in 2 samples of 7 yr old twins a. Low socioeconomic status was 10% b. Middle to high socioeconomic status was about 70% Downloaded by Micah Clado ([email protected])