Sexual attraction

Evolutionary Explanations for Partner Preferences

  • The specification includes:

    • The evolutionary explanations for partner preferences, including the connection between sexual selection and human reproductive behavior.

Charles Darwin's Theory

  • Darwin's theory of evolution is based on natural selection but does not completely explain certain characteristics in animals.

  • Example: Male peacocks have large, elaborate tails that may threaten survival but persist.

  • Darwin's theory of sexual selection:

    • This theory addresses how certain traits contribute to reproductive success rather than survival.

    • The Handicap Principle (Zahavi, (1975)): Suggests that elaborate traits are a 'handicap' that demonstrates genetic superior strength, as the individual survived despite the disadvantage.

    • The Sexy Son Hypothesis (Fisher, (1930)): Suggests females choose males with desirable traits so their sons will inherit them, ensuring future reproductive success for the lineage.

Key Terms

  • Sexual Selection

    • An evolutionary explanation for partner preference where attributes or behaviors enhancing reproductive success are passed on and may become intensified in future generations.

  • Human Reproductive Behavior

    • Any behaviors related to reproduction opportunities and enhancing gene survival; includes mechanisms like mate choice and mate competition.

Application Example: Three Relationships

  • Kaley ((25)) married to Ryan ((60)); they are yet to have children.

  • Nicole ((53)) with Keith ((29)); they do not let age differences affect their relationship; Nicole has three children from a previous marriage.

  • Benedict ((30s)) and Eddie ((30s)) are civil partners looking to adopt.

Questions

  1. Explain these relationships with evolutionary explanations of human reproductive behavior.

  2. Discuss behaviors potentially unexplainable by evolutionary arguments.

Sexual Selection

  • Darwin ((1871)) defined sexual selection as the process enhancing successful reproduction rather than survival.

  • Example: Male peacocks’ tails signal genetic fitness.

  • Claim: Females choosing males with such traits produce stronger offspring, perpetuating the trait.

Anisogamy

  • Refers to the difference between male and female reproductive cells:

  • Male Gametes (Sperm):

    • Small, agile, produced in large quantities ((100) million per ejaculation).

    • Less energy required.

  • Female Gametes (Eggs):

    • Large, static, limited quantities produced over a specific timeframe ((1) per month).

    • Require significant energy investment.

  • Implication of Anisogamy:

    • Fertile males are abundant, but fertile females are typically rarer, influencing partner selection significantly. This leads to different mating strategies.

Types of Sexual Selection

  • Inter-sexual Selection

    • Between sexes: Males/females select partners.

    • Preferred by females due to quality over quantity; females invest more in offspring care (Post-zygotic investment).

    • Females become choosy, seeking genetically fit partners to ensure the survival of their limited eggs.

  • Intra-sexual Selection

    • Occurs within a sex: Males compete for mating rights.

    • Males exhibit aggressive traits that boost reproductive success, emphasizing competition.

    • Dimorphism: The physical difference between males and females (e.g., larger males) resulting from competition.

Evaluation of Sexual Selection

  • Research Support for Inter-sexual Selection

    • Clark and Hatfield ((1989)) showed female choosiness: 0\% of females agreed to sleep with a stranger, while 75\% of males did.

  • Research Support for Intra-sexual Selection

    • Buss ((1989)) found consistent sex-based differences across 33 countries: males valued youth/chastity, females valued resource-related ambitions.

  • Social and Cultural Influences

    • Evolutionary theories often overlook social progression and the 'waist-to-hip ratio' research by Singh ((1993)), which suggests a ratio of 0.7 is universally attractive as it signals fertility.

Factors affecting Attraction: Self-disclosure

  • Definition: Revealing personal information that deepens romantic connections over time.

  • Social Penetration Theory (Altman & Taylor, (1973)):

    • Breadth and Depth: Like peeling an onion, layers of information go from superficial to intimate.

    • Reciprocity (Reis & Shaver, (1988)): For a relationship to develop, disclosure must be mutual and responsive.

Factors affecting Attraction: Physical Attractiveness

  • The Halo Effect: A cognitive bias where we assume that because people are physically attractive, they also possess other positive personality traits (e.g., kindness, intelligence).

  • The Matching Hypothesis (Walster et al., (1966)):

    • People choose partners of a similar level of attractiveness to their own to balance the desire for the 'best' mate with the fear of rejection.

  • Neotenous Features: Evolutionary preference for 'baby-face' features (large eyes, small nose) in females as they trigger protective instincts and signal youth.

Filter Theory (Kerckhoff and Davis, (1962))

  • Focuses on the process of narrowing down the 'field of availables' to a 'field of desirables' through three filters:

    1. Social Demography: Geographic location, social class, and education level.

    2. Similarity in Attitudes: Shared values and beliefs (essential for short-term progress).

    3. Complementarity: Partners having traits that the other lacks, providing a sense of 'wholeness' (essential for long-term commitment).