Nature and Nurture

Learning Objective #29

  • Contrast Nature and Nurture

    • Nature: Refers to heredity, specifically the influence of genes.

    • Nurture: Refers to experience, particularly how learning and environmental factors shape behavior.

Learning Objective #30

  • Define some basic genetic terms:

    • Chromosome: Structures within cells that contain DNA; humans have 23 pairs.

    • DNA: Deoxyribonucleic acid, the molecule that carries genetic instructions.

    • Gene: A segment of DNA that contains instructions for building proteins.

    • Genotype: The set of genes an individual has inherited.

    • Phenotype: Observable physical and behavioral characteristics of an individual, resulting from the interaction of genotype with the environment.

Genetics Basics

  • Chromosomes:

    • Each cell contains 23 pairs of chromosomes, one from each parent.

    • Chromosomes consist of coiled strands of DNA.

  • Genes:

    • Segments of DNA with instructions for building protein molecules.

  • Roles of Genotype and Phenotype:

    • Genotype: Represents the genetic makeup inherited from parents.

    • Phenotype: Represents the physical manifestations and behaviors influenced by the genotype and environmental interactions.

Genetics Review

  • Genetic Vocabulary and Definitions:

    • A segment of DNA containing instructions for building a protein is called a Gene (Answer: c).

    • Aspects NOT part of your phenotype include:

    • B (the genes for brown eyes).

Food for Thought

  • “We share half our genes with the banana.” - Robert May, 2001.

  • Human DNA is 99.4% similar to that of chimpanzees at functionally important sites (Wildman et al., 2003).

Learning Objective #31

  • Define Behavior Genetics:

    • The study of how genetic and environmental differences influence behavior.

Behavioral Genetics: Methods

  • The field utilizes various research methodologies including:

    • Family Studies: Analyzing traits through family trees.

    • Twin Studies: Comparing concordance rates between monozygotic and dizygotic twins.

    • Adoption Studies: Studying children raised apart from biological parents to assess genetic influence.

    • Molecular Genetic Studies: Investigating specific genes and their roles in behavior.

Behavioral Genetics: Assumptions

  1. Genes contribute to individual behavioral differences.

  2. Environment interacts with genetic predispositions to influence behaviors.

  3. Phenotype emerges from the interplay of genotype and environment.

  4. There are various Gene-Environment Interactions which affect phenotype.

Types of Gene-Environment Interactions

  • Passive: Genetic traits shape environments; individuals receive environments that match their genetics.

  • Active: Individuals actively seek experiences that correspond to their genetic predispositions.

  • Epigenetic: Environmental factors can turn genes on or off, influencing gene expression over time.

Epigenetic Effects Examples

  • Genes related to Depression may activate only under specific environments, like stressful scenarios.

  • Genes related to Schizophrenia may also respond to prenatal factors, infections, and delivery complications, impacting the likelihood of expressing the disorder.

Learning Objective #32

  • Methods of Family and Twin Studies:

    • Early family studies traced disorders through familial ties, establishing patterns of inheritance for psychological disorders.

Family Studies Findings

  • Relationship and Gene Sharing:

    • Child/Parent: 50%

    • Full Sibling: 50%

    • Grandparent/Grandchild: 25%

    • Aunt/Uncle/Niece/Nephew: 25%

    • First Cousins: 12.5%

Family Studies: Schizophrenia and Bipolar Disorder Prevalence Estimates:

  • General population risk for schizophrenia: 1 in 100

  • If a biological parent has schizophrenia: 6 in 100

  • If both biological parents have schizophrenia: 45 in 100

  • If a sibling has the disorder: 9-13 in 100

  • For MZ twins: 40-50 in 100; DZ twins: 17-20 in 100.

Twin Studies Overview

  • Monozygotic Twins: Share 100% genetic material (developed from a single fertilized egg).

  • Dizygotic Twins: Share 50% genetic material (developed from separate fertilized eggs).

Twin Studies Data Analysis

  • Compare behavioral correlations between MZ and DZ twins to assess genetic influence on traits.

Learning Objective #33

  • Surprising Findings from Twin Studies:

    • MZ twins show more similarity across various traits like personality, mental health, intelligence, etc., compared to DZ twins.

Learning Objective #34

  • Explain Heritability:

    • A measure of how much of the variability between individuals in a sample is attributable to genetic differences.

    • Heritability values range from 0 (no genetic contribution) to 1.0 (entire variability due to genetics).

    • Moderate heritability: ~.3

    • Fairly high heritability: ~.5

    • Very high heritability: ~.8

Heritability Misinterpretations

  1. Heritability refers to groups, not individuals.

  2. High heritability does not imply low environmental influence.

  3. Heritability does not account for the possible modifiability of traits through environmental changes.

Heritability Examples and Misinterpretations

  • Findings indicate high heritability for traits like schizophrenia, but this does not mean the environment has no effect.

  • Traits with high heritabilty remain susceptible to environmental shifts, affecting average outcomes.

Learning Objective #35

  • Adoption Studies:

    • Explore relationships between adopted children and their biological versus adoptive parents.

Surprising Outcomes from Adoption Studies

  • Intelligence similarities between adopted children and biological parents increase over time, particularly highlighting the role of stability in genetic inheritance.

  • Environment plays a significant role, especially in variable conditions, indicating that enriched environmental factors promote IQ development.

Molecular Genetic Studies

  • Genome-Wide Association Studies (GWAS) investigate large genetic samples to identify genetic variations (SNPs) correlated with various diseases.

Summary of Behavioral Genetics

  • Focuses on the intertwining of genetics and environment in shaping behavior, employing various methodologies.

  • Provides insights into misconceptions regarding heritability and individual differences in psychological traits.

Learning Objective #36

  • Evolutionary Psychology Assumptions:

    • Behaviors are partially genetically influenced while exhibiting individual variations.

    • Variations boosting survival and reproduction get transmitted to future generations.

Evolutionary Psychology Overview

  • Applies Darwinian natural selection to decode behaviors and mental processes rooted in survival and reproduction.

Learning Objective #37

  • Explanations of Behavior through Evolutionary Approach:

    • Overeating is viewed as an evolutionary survival trait for calorie scarcity scenarios.

    • Parental investment and affection towards babies enhance their survival likelihood.

    • Women's superior search task capabilities relate to ancestral roles in gathering food.

Sexual Attraction Contexts

  • Face Attractiveness: Preference for averaged faces correlates with lower genetic mutation risks.

  • Sexual Strategies Theory: Differences in reproductive strategies stemming from gender-based parental investment disparities.

  • Women typically prioritize appearance while men emphasize financial stability in mate selection due to societal roles.

Alternative Perspectives

  • Differences in mating preferences can also be explained by social role theory, emphasizing the impact of societal structures on mate selection.

Learning Objective #39

  • Criticisms of Evolutionary Perspectives:

    • Hindsight explanations can lead to oversimplifications—and potential justification of undesirable behaviors.

Summary of Evolutionary Psychology

  • The field offers frameworks for understanding behaviors from a survival and reproduction viewpoint but faces critique and limitations regarding empirical support and applicability.

Culture Defined

  • Culture: A shared pattern of meanings and behaviors transmitted through generations, encompassing individual identity, emotional frameworks, and moral values.

Learning Objective #41

  • Methodological Distinctions:

    • Ethnographic Studies: Participatory immersion in cultural settings.

    • Cross-Cultural Studies: Comparative evaluations across different cultural backgrounds using quantitative data.

WEIRD Problem in Psychology

  • Most psychological research is conducted on WEIRD (Western, Educated, Industrialized, Rich, Democratic) populations, which does not represent global diversity.

Individualism-Collectivism Dimension

  • Describes the cultural tendency to emphasize individual autonomy versus group interdependence, significantly influencing behavior patterns, leading to varied social interactions and priorities.

Individualism-Collectivism Characteristics

  • Individualism: Focus on self-worth, uniqueness, and independent decision-making practices.

  • Collectivism: Emphasizes social harmony, fulfillment of communal duties, and shared responsibilities.

Summary of Culture

  • Culture shapes psychological processes across various realms (from morality to perception) and is fundamental in understanding human social interactions and psychological constructs.