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Stanford University Lecture Notes

Jul 19, 2024

Stanford University Lecture

Midterm Overview and Second Half of the Course

  • Midterms have been completed.
  • Organizing readings and book recommendations for the second half of the course.
  • Transition to new subjects like sexual behavior, aggression, competition, cooperation, etc.
  • Strategy: analyze behaviors across species, examining various time points leading up to behaviors (e.g., brain activity, environmental triggers, hormone levels, genetics).
  • Key themes: interactions between categorical buckets and chronic hormonal effects on behavior.

Sexual Behavior

  • Proximal vs Distal Explanations:
    • Proximal: Feels good (immediate senses and feedback).
    • Distal: Passing on genes, evolutionary purposes.
  • General Patterns in Sexual Behavior:
    • Fixed action patterns in various species (e.g., pelvic thrusting, orgasms, lordosis reflexes).
    • Species-specific behaviors to ensure mating with the same species.
  • Ethological Principles:
    • Studying animals in their natural setting to understand behaviors.
  • Key Terms:
    • Libido: Sexual arousal and motivation.
    • Proceptivity: Active behaviors attracting a mate.
    • Receptivity: Passive acceptance of advances.
    • Attractivity: How attractive an individual is to potential mates.
  • Human-Specific Sexual Behaviors:
    • Non-reproductive sex: Also observed in Bonobos and some dolphins.
    • Foreplay, homosexuality, egalitarian sex, cheating, romance.
    • Introduction of complex behaviors (e.g., mastubration, fantasy, marriage and monogamy).
    • Neurobiology of sexual behavior: Limbic system's role in regulating sexual behaviors, with specific roles for the hypothalamus, amygdala, and other areas in both sexes.
    • Differences in sexual behaviors across genders.
  • Hormonal Responses to Sexual Behavior:
    • Release of oxytocin and vasopressin forming bonds in females and males respectively.
    • Dopamine's role in reward and pleasure.
    • Differences in testosterone and androgen levels affecting behaviors and responses.
    • Social and biological implications of hormones and neurobiology (monogamy, attraction, etc).

Neurobiology of Sexual Orientation

  • Key Study: Size of a hypothalamic nucleus varies in gay vs straight men.
    • Finger Ratio and Auto-acoustic Reflex: Differences between straight and gay individuals.
    • Transsexuality: Brain structures matching gender identity rather than biological sex.

Pheromonal Communication

  • Role of Pheromones: Sexual attraction and arousal, carrying species-specific information.
    • Generating and Perceiving Pheromones: Affected by hormones.
    • Perfumes: Often developed from male sweat and pheromones; marketed towards women.
    • Environmental (sensory) Triggers: Visual, tactile, and olfactory cues releasing fixed action patterns of sexual behavior in various species.

Conclusion

  • Transition to understanding behaviors triggered by environmental stimuli and pheromones.