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14. What Motivates Us: Sex

YaleCourses・34 minutes read

Sex is highly valued by Americans, despite spending minimal time on it, impacting various aspects of life. The text delves into the evolutionary, biological, and psychological differences between males and females, discussing parental investment, sexual preferences, and differences in aggression and empathy.

Insights

  • The average American spends only four minutes and three seconds on sex daily, despite ranking it as their favorite activity, showcasing a significant disparity between perception and reality.
  • Evolutionary theories explain sex differences between males and females, emphasizing differences in social intelligence, aggression, and empathy, as well as the impact of parental investment on psychological and physiological variances, highlighting the intricate biological and evolutionary underpinnings of human behavior and relationships.

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Recent questions

  • Why do animals have two sexes?

    Animals have two sexes to ensure genetic diversity and increase the chances of survival for offspring. Despite the evolutionary mystery of losing half their genes with each offspring, having two sexes allows for genetic recombination, leading to variations that can be beneficial in adapting to changing environments and resisting diseases.

  • How do males and females differ in sexual preferences?

    Males tend to be more receptive to anonymous sex due to lower parental investment, while females are more selective in choosing mates who exhibit qualities of good fathers, protectors, and caretakers. These differences stem from evolutionary strategies aimed at maximizing reproductive success and offspring survival.

  • Why are males typically larger and more aggressive than females?

    Evolutionary logic dictates that males have evolved to be larger, more aggressive, and possess special weapons for reproductive access, while females are choosy in selecting the best mates for offspring survival. This difference in physical characteristics and behavior is driven by the need to compete for reproductive opportunities and ensure genetic success.

  • What factors influence attractiveness in humans?

    Beauty in humans is considered a universal signal of youth and health, with specific physical attributes like large eyes and clear skin being universally attractive. Averaging faces together creates a universally attractive face, signaling a preference for symmetry and health, while feminizing average faces can enhance attractiveness.

  • Is sexual orientation a conscious choice?

    Sexual orientation is not a conscious choice, as individuals do not decide who they are attracted to. Studies suggest differences in sexual and romantic fantasies between gay and straight individuals before puberty, indicating that sexual orientation is likely influenced by a combination of genetic predisposition and prenatal experiences.

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Summary

00:00

Sex: A Brief Look at Human Behavior

  • People often claim sex is their favorite activity, but data shows the average American spends only four minutes and three seconds on sex daily.
  • Americans rank sex above sports, fishing, and other activities in terms of enjoyability.
  • Despite minimal time spent on sex, its importance is immense, impacting marriage, family, aggression, competition, art, and more.
  • The evolutionary mystery of why animals have two sexes, despite losing half their genes with each offspring, is puzzling.
  • Sex differences between males and females are explored theoretically and empirically, including differences in social intelligence, aggression, and empathy.
  • Sexual attractiveness and the origins of sexual preference, such as being straight, gay, or bisexual, are discussed.
  • The moral implications of sexual behavior as a biological adaptation for gene spreading are considered.
  • The inevitability of genetic causes versus environmental causes is debated, emphasizing that genetic does not mean inevitable.
  • The difference between males and females is not just physical but also involves parental investment, leading to various psychological and physiological differences.
  • Evolutionary logic explains why males are typically larger, more aggressive, and have evolved special weapons for reproductive access, while females are choosy and seek the best mates for offspring survival.

16:20

Parental Investment and Sexual Dimorphism in Species

  • In some species, parental investment can be switched, leading to cases where males invest more than females, resulting in asymmetry.
  • Examples like pipefish show males taking eggs into a pouch, indicating higher investment than females.
  • Female pipefish are larger, fight more, and compete for male attention due to differing parental investment.
  • Elephant seals have males four times larger than females due to competition for harems, while gibbons are similar in size due to monogamy.
  • In some species, like gibbons, it's advantageous for males to care for offspring, leading to equal parental investment.
  • Human males are about 15% larger than females, suggesting male-male competition for access to females.
  • Male sex hormones like testosterone increase aggressiveness in humans and other primates.
  • Evolutionary history suggests women were not entirely monogamous, leading to male competition for sperm production.
  • Men tend to be more physically violent than women from the womb to adulthood, with higher rates of aggression.
  • Studies show differences in sexual preferences between men and women, with males more receptive to anonymous sex and females more selective due to differing parental investment.

31:35

Evolutionary Factors in Attraction and Gender Differences

  • Women are wired to find males who are good fathers, protectors, and caretakers attractive.
  • Men are interested in similar qualities but also focus on the ability to have children.
  • Evolutionarily, there is a significant difference between a twenty-year-old and a fifty-year-old male in terms of offspring potential.
  • Beauty is considered a universal signal of youth and health, with specific physical attributes like large eyes and clear skin being attractive.
  • Average faces are considered attractive due to their lack of deformities and deviations.
  • Averaging faces together creates a universally attractive face, signaling a preference for symmetry and health.
  • Feminizing average faces can enhance attractiveness, with variations in preferences based on ovulation cycles.
  • Social factors, such as gender self-segregation and name biases, can influence male and female differences.
  • Men are suggested to be less empathetic and more prone to social cognition disorders compared to women.
  • Controversies exist regarding sex differences in math and science aptitude, with debates on intrinsic aptitude and variability.

47:20

Origin of Sexual Orientation: A Genetic Puzzle

  • Sexual orientation is not a conscious choice, as individuals do not decide who they are attracted to, with studies suggesting differences in sexual and romantic fantasies between gay and straight individuals before puberty.
  • While there is a genetic predisposition towards homosexuality, it cannot be solely genetic as identical twins do not always share the same sexual orientation, indicating a possible influence of prenatal experiences.
  • Exclusive homosexuality poses an evolutionary mystery as it does not seem to align with biological adaptation, raising questions about why some individuals do not desire sexual relations with the opposite sex.
  • The challenge posed to students is to solve the puzzle of exclusive homosexuality, emphasizing the need for responses to be grounded in facts discussed in lectures and readings, with consideration for cross-species data on sexual preferences in animals.
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