CHAPTER 3: BIOLOGY AND BEHAVIORNATURE AND NURTURE- Everything about you is a joint consequence of the interaction between the genetic material you inherited from your parents and the environments you have experienced o Heredity and Environment work in concert to influence both the waysin which you are like other people and the ways in which you are uniqueo Genome- complete set of geneso Development results from the close and continual interplay of nature and nurture (genes and experiences) - Genetic and Environmental Factorso Variability contributing to individual differences arises through all of these pathways:1. Genotype of parent2. Genotype of child3. Phenotype of child4. Phenotype of parent5. Environment of childo Model of Hereditary and Environmental Influences Genotype- genetic material an individual inherits Phenotype- observable expression of the genotype including both body characteristics and behavior Environment- every aspect of the individual and his or her surroundings other than the genes themselves- Genotypes, Phenotypes, and Environments are involved in four fundamental relations in the development of every child1. Parents genetic contribution to the child’s genotypea. Chromosomes Genes: sections of chromosomes that are the basic units of heredity for all living thingsb. Transmission of genetic material (chromosomes and genes)c. Human Heredity: total of 46 chromosomes (egg:23, sperm:23)d. Sex determination: sex chromosomes1. Females have XX males have XY e. Mechanisms of Diversity and Individuality1. Mutation- change in a DNA section some of which are spontaneous while others are due to environmental factors. Genes are incorrectly copied2. Random assortment- promotes variability and accounts for different genotypes. Representation of the genes have 8.4 million different combinations3. Crossing over- swapping of genetic material across chromosomes2. The contribution of the child’s genotype to his or her own phenotypea. Although every cell in the body contains copies of all the genes from your parents only some of the genes are expressed (genetic contribution to the phenotype)b. Gene expression-Developmental Changes1. A given gene influences development and behavior only when it is turned on and human development proceeds normally if genes get switched on and off atproper times and places.2. Regulator genes- controls the switching on and off of genes (affected by external factors)3. Polygenetic effects- traits governed by more than one gene (autism?)c. Gene expression- dominance patterns1. Alleles- two or more different forms of a gene2. Dominant allele- the allele that if present gets expressed3. Recessive allele- allele that is not expressed if a dominant allele is present4. Homozygous- having two of the same allele for a trait5. Heterozygous- having two different alleles for a trait6. Polygenic inheritance- several different genes contribute to any given phenotypic outcome7. Epigenetic effects- changes in genes expression due to environmental factors3. The contribution of the child’s environment to his or her phenotypea. Norm of reaction- all the phenotypes that could theoretically result from a given genotype in relation to all the environments in which it could survive and developb. Childs observable characteristics result from the interaction of environmental factors and their genetic makeupc. Parental contributions to the child’s environment depend heavily on the experiences, interactions and encouragement they offer. 1. PKU2. MAOA- those who experienced maltreatment were more likely to be antisocial and this was much higher for those who had a inactive MAOA gene3. Differential susceptibility- Based off of genes, nature, and environment. Beyond only the genes4. The influence of the child’s phenotype on his or her environmenta. Active child theme- the child as a source of his or her own development1. Actively evoke certain kinds of responses from others2. Actively select their surroundings and experiences that match their interests, talents, and personality characteristics- Behavior Genetics-Goal is to separate behavior variability into genetic and environmental components and describe their interactiono Heritable- refers to any characteristics of traits that are influenced by heredity Heritability- statistical estimate of how much of the measured variance on a trait among individuals in a given population is attributable to genetic differences among those individuals Applies to a given POPULATION- tells us nothing about differences between groupso Polygenic- affected by the combination of many genes (aggression, shyness, sociability)o Multifactorial- affected by a host of environmental factors as well as genetic oneso Genetic and Environmental Contributions to Differences Observed1. What extent are genetic factors important for a given trait orbehavior? In other words children should be more similar totheir parents and siblings than other relatives2. To the extent that shared environmental factors are important, individuals that have been reared together should be more similar than those who haven’t 3. Examples:- Family studies- a trait of interest is measured among groups of people who vary in genetic relatedness- Twin studies- twins who grow up together have a high degree of similarity between genetics and environment. Genetic factors are substantially responsible if a correlation between identical twins on a train is higher than fraternal twins (ID, reaction to stress, and traditionalism were similar for twins reared APART)- Adoption studies- correlation for twins reared apartare similar for those reared together it suggests environmental factors have little effectBRAIN DEVELOPMENT- Orderly, cumulative and directional- Structures of the Braino Neurons- constitute the gray matter of the brain. Specialized for sending and receiving electrical messages between the brain and all parts of the body Sensory neurons- transmit information from sensory receptors that detect stimuli in the external environment or within the body Motor neurons- transmit information from the brain to muscles and glands Interneurons- act as intermediaries between sensory and motor neurons Cell body- contains the basic biological material that keeps theneuron functioning (gray matter) Dendrites- fibers that receive input from other cells and conduct it toward the cell body in the form of electrical impulses (gray matter) Axon- a fiber
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