1.1 Interaction of Environment & Heredity

Interaction of Environment & Heredity

  • Unit 1: Biological Bases of Behavior

Nature vs. Nurture Debate

  • Nature (Genetics): Refers to genetic predispositions influencing physical appearance and personality traits.
  • Nurture (Environment): Encompasses all external influences, including:
    • Early childhood experiences
    • Parenting styles
    • Social interactions
    • Cultural context

Heredity Understanding

  • Genetic Predisposition: The likelihood of developing certain traits or behaviors based on genetics.
    • Example: A person may have a genetic predisposition to diabetes.
  • Environmental Triggers: Certain environments can activate genetic factors.

Examples of Nature vs. Nurture

Genetics vs. Environment in Traits:

  • Height: Can be influenced by genetics and nutrition.
  • Creativity: Cultivated through environment and experiences.
  • Temper and Aggressive Behavior: Genetics may increase risk, but environment can amplify or mitigate these traits.
  • Obesity: Driven by genetic factors, but lifestyle and environment play pivotal roles.
  • Personality: Both hereditary traits and upbringing influence personality development.
  • Alcoholism: Genetic susceptibility, but external factors like social context play a significant role.
  • Political Opinions: Influenced by both inherited traits and cultural upbringing.
  • Musical Ability: Can be nurtured through lessons and support or limited by lack of exposure.

Case Study: Charles Whitman

  • Explores the question: Are criminals born or made?
    • Suffered from headaches and irrational thoughts, unsure of his mental state.
    • Left a note asking for his brain to be examined after death.
    • Autopsy revealed a glioblastoma affecting emotional regulation areas in the brain.

Evolutionary Perspective

  • Natural Selection: Behaviors aiding survival and reproductive success are more likely to be passed down.
  • Psychological Adaptations
    • Development of traits like dietary preferences and phobias.
    • Example: Phobias toward snakes are advantageous in terms of survival.

Important Figures in Evolutionary Psychology

  • Charles Darwin (1809-1882): Key in understanding adaptation within species.
  • Francis Galton (1822-1911): Focused on applying genetic principles to social outcomes.
    • Eugenics: The idea that society can be improved through selective breeding.

Heredity and Gene Function

  • Genes: The fundamental units of heredity, responsible for biological traits.
    • Humans have approximately 24,000 genes, with most being similar across individuals.
  • Epigenetics: Studies changes in gene expression influenced by environmental factors.
    • Suggests that genes can be turned on or off by lifestyle and exposure.

Research Methods in Genetics

Types of Research

  • Twin Studies: Examine genetic and environmental influences by comparing monozygotic (identical) and dizygotic (fraternal) twins.
  • Family Studies: Investigate familial resemblance for traits to determine genetic links.
  • Adoption Studies: Compare traits of adopted individuals with their biological and adoptive parents.

Twin Studies Specifics

  • Monozygotic Twins: Genetically identical twins from a single egg.
  • Dizygotic Twins: Fraternal twins who share approximately 50% of their genetic material.
  • Useful for exploring the heritability of traits and disorders.
    • For instance, increased similarities in intelligence and certain mental disorders among identical twins can suggest genetic influence.