Genetics, Evolution, and Behavior: Understanding Individual Differences
This module delves into the fundamentals of genetics, evolutionary psychology, and behavior genetics to explain how our DNA, genes, and environment influence our individual differences. It explores the roles of chromosomes, DNA, genes, and the human genome in shaping our behaviors. Twin and adoption studies are highlighted as valuable tools to understand the interplay of nature and nurture in shaping who we are.
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Module 6 Genetics, Evolutionary Psychology, and Behavior Josef F. Steufer/Getty Images
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences 6-1: WHAT ARE CHROMOSOMES, DNA, GENES, AND THE HUMAN GENOME? HOW DO BEHAVIOR GENETICISTS EXPLAIN OUR INDIVIDUAL DIFFERENCES? Environment: Every nongenetic influence, from prenatal nutrition to the people and things around us Heredity: The genetic transfer of characteristics from parents to offspring Behavior genetics: Study of the relative power and limits of genetic and environmental influences on behavior
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Genes: Our Codes for Life Chromosomes: Threadlike structures made of DNA molecules that contain the genes DNA (deoxyribonucleic acid): Complex molecule containing the genetic information that makes up the chromosomes Genes: Biochemical units of heredity that make up chromosomes; segments of DNA capable of synthesizing proteins Genome: All the genetic material in an organism s chromosomes When genes are expressed, they provide the code for creating the proteins that form our body s building blocks
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Twin and Adoption Studies 6-2: HOW DO TWIN AND ADOPTION STUDIES HELP US UNDERSTAND THE EFFECTS AND INTERACTIONS OF NATURE AND NURTURE? Identical Versus Fraternal Twins Identical (monozygotic) twins: Develop from a single fertilized egg that splits in two, creating two genetically identical organisms Identical twins share the same conception and uterus, and usually the same birth date and cultural history
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Twin and Adoption Studies
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Twin and Adoption Studies Identical Versus Fraternal Twins Fraternal (dizygotic) twins: Develop from separate fertilized eggs Genetically no closer than brothers and sisters, but they share a prenatal environment Studies of twins in adulthood show that identical twins are more alike than fraternal twins in: Having disorders, such as autism spectrum disorder Personality traits such as extraversion (sociability) and neuroticism (emotional instability).
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Twin and Adoption Studies Separated Twins Similarities found in identical twins despite being raised in different homes: Personality, styles of thinking and relating Abilities/intelligence test scores Attitudes Interests, tastes Specific fears Brain waves, heart rate
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Twin and Adoption Studies Biological Versus Adoptive Relatives Studies conducted with adopted children for whom the biological relatives are known Adopted children seem to be more similar to their genetic relatives than their adoptive relatives The environment shared by a family s children has virtually no discernible impact on their personalities. Does the home environment have any impact?
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Twin and Adoption Studies Biological Versus Adoptive Relatives Despite the strong impact of genetics on personality, parenting has an influence on: Religious beliefs Values Manners Attitudes Politics Habits
Genetics, Evolutionary Psychology, and Behavior Behavior Genetics: Predicting Individual Differences Gene-Environment Interaction 6-3: HOW DO HEREDITY AND ENVIRONMENT WORK TOGETHER? Genes and environment nature and nurture work together Genes are self-regulating; rather than acting as blueprints that lead to the same result no matter the context, genes react Genes and experience interact Epigenetics: The study of environmental influences on gene expression that occur without a DNA change
EPIGENETICS INFLUENCES GENE EXPRESSION Life experiences beginning in the womb lay down epigenetic marks often organic methyl molecules that can affect the expression of any gene in the associated DNA segment. (From Champagne, 2010.)
Genetics, Evolutionary Psychology, and Behavior Evolutionary Psychology: Understanding Human Nature 6-4: HOW DO EVOLUTIONARY PSYCHOLOGISTS USE NATURAL SELECTION TO EXPLAIN BEHAVIOR TENDENCIES? Behavior genetics explore the genetic and environmental roots of human differences. Evolutionary psychologists instead focus mostly on what makes us so much alike as humans.
Genetics, Evolutionary Psychology, and Behavior Evolutionary Psychology: Understanding Human Nature Evolutionary psychology: The study of the evolution of behavior and the mind, using principles of natural selection. Evolutionary psychologists use Charles Darwin s principle of natural selection to understand the roots of behavior and mental processes Natural selection: The principle that those chance inherited traits that better enable an organism to survive and reproduce in a particular environment will most likely be passed on to succeeding generations Nature has indeed selected advantageous variations from the new gene combinations produced at each human conception plus the mutations (random errors in gene replication) that sometimes result. But especially in humans, genes and experience together wire the brain.
Genetics, Evolutionary Psychology, and Behavior Evolutionary Psychology: Understanding Human Nature Natural Selection and Adaptation Natural selection and adaptation Genes selected during our ancestral history give us a great capacity to learn and therefore to adapt to life in varied environments. The tight genetic leash that predisposes a dog s retrieving, a cat s pouncing, or a bird s nesting is looser in humans. Adaptive flexibility in responding to different environments contributes to the ability to survive and reproduce.
Evolutionary Psychology: How Natural Selection Works Conditions make it difficult for individuals with some traits (some versions of those genes) to survive long enough to reproduce. Begin with a species genome, which contains a variety of versions of genes that shape traits. Other individuals thus have their traits and genes selected to spread in the population.
Genetics, Evolutionary Psychology, and Behavior Evolutionary Psychology: Understanding Human Nature Evolutionary Success Helps Explain Similarities Our Genetic Legacy As success-enhancing genes were selected over time, behavioral tendencies and thinking and learning capacities emerged that prepared our Stone Age ancestors to survive, reproduce, and send their genes into the future. As inheritors of this prehistoric genetic legacy, we are genetically predisposed to behave in ways that promoted our ancestors surviving and reproducing, ways that may be mismatched with our contemporary lifestyle. In what ways might this be problematic?
Genetics, Evolutionary Psychology, and Behavior Evolutionary Psychology: Understanding Human Nature Evolutionary Success Helps Explain Similarities Evolutionary Psychology Today Darwin s theory of evolution has become one of biology s organizing principles The theory lives on in the second Darwinian revolution, the application of evolutionary principles to psychology Darwin anticipated this, foreseeing open fields for far more important researches. Psychology will be based on a new foundation.
