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This chapter explores the role of genes and environment in shaping behavior. It covers topics such as genetics, evolutionary psychology, behavior genetics, and the influence of the environment. It also delves into the nature and nurture of gender, including the importance of chromosomes, hormones, and social learning.
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Myers’ PSYCHOLOGY (7th Ed) Chapter 3 The Nature and Nurture Of Behavior James A. McCubbin, PhD Clemson University Worth Publishers
Genes: Our Biological Blueprint • Chromosomes • threadlike structures made of DNA that contain the genes • DNA (deoxyribonucleic acid) • complex molecule containing the genetic information that makes up the chromosomes • has two strands-forming a “double helix”--held together by bonds between pairs of nucleotides
Genes: Our Biological Blueprint • Genes • biochemical units of heredity that make up the chromosomes • a segment of DNA capable of synthesizing a protein • Genome • the complete instructions for making an organism • consisting of all the genetic material in its chromosomes
Nucleus Chromosome Gene Cell DNA Genes: Their Location and Composition
Evolutionary Psychology • Natural Selection • the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations • Mutations • random errors in gene replication that lead to a change in the sequence of nucleotides • the source of all genetic diversity
Evolutionary Psychology • Evolutionary Psychology • the study of the evolution of behavior and the mind, using the principles of natural selection • Gender • in psychology, the characteristics, whether biologically or socially influenced, by which people define male and female
Evolutionary Psychology • Men preferred attractive physical features suggesting youth and health • Women preferred resources and social status
Behavior Genetics • Behavior Genetics • study of the relative power and limits of genetic and environmental influences on behavior • Environment • every nongenetic influence, from prenatal nutrition to the people and things around us
Identical twins Fraternal twins Same sex only Same or opposite sex Behavior Genetics • Identical Twins • develop from a single fertilized egg that splits in two, creating two genetically identical organisms • Fraternal Twins • develop from separate eggs • genetically no closer than brothers and sisters, but they share the fetal environment
Behavior Genetics • Temperament • a person’s characteristic emotional reactivity and intensity • Heritability • the proportion of variation among individuals that we can attribute to genes • may vary, depending on the range of populations and environments studied
Behavior Genetics • Interaction • the dependence of the effect of one factor (such as environment) on another factor (such as heredity) • Molecular Genetics • the subfield of biology that studies the molecular structure and function of genes
Environmental Influence • Two placental arrangements in identical twins
Rat brain cell Impoverished environment Rat brain cell Enriched environment Environmental Influence • Experience affects brain development
Environmental Influence • A trained brain
Environmental Influence • Culture • the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next • Norm • an understood rule for accepted and expected behavior
Environmental Influence • Personal Space • the buffer zone we like to maintain around our bodies • Memes • self-replicating ideas, fashions, and innovations passed from person to person
The Nature and Nurture of Gender • X Chromosome • the sex chromosome found in both men and women • females have two; males have one • an X chromosome from each parent produces a female child • Y Chromosome • the sex chromosome found only in men • when paired with an X chromosome from the mother, it produces a male child
The Nature and Nurture of Gender • Testosterone • the most important of the male sex hormones • both males and females have it • additional testosterone in males stimulates • growth of male sex organs in the fetus • development of male sex characteristics during puberty • Role • a set of expectations (norms) about a social position • defining how those in the position ought to behave
The Nature and Nurture of Gender • Gender Role • a set of expected behaviors for males and females • Gender Identity • one’s sense of being male or female • Gender-typing • the acquisition of a traditional masculine or feminine role
The Nature and Nurture of Gender • Gender and Culture
The Nature and Nurture of Gender • Social Learning Theory • theory that we learn social behavior by observing and imitating and by being rewarded or punished • Gender Schema Theory • theory that children learn from their cultures a concept of what it means to be male and female and that they adjust their behavior accordingly
The Nature and Nurture of Gender • Two theories of gender typing