Lecture+7+Slides

Basic Principles of Evolutionary Theory

• Darwin's Proposal:

  • Darwin proposed two processes through which evolution occurs:

    1. Natural Selection

    2. Sexual Selection

Natural Selection

• Definition:

  • A process through which organisms develop characteristics that enhance their ability to survive.

• Process:

  • Organisms with advantageous characteristics are more likely to survive to reproductive age and pass these traits on to the next generation.

• Impact Over Generations:

  • Over successive generations, survival-enhancing characteristics increase in frequency, becoming common within the species.

  • Offspring inheriting these traits are also more likely to survive and continue the cycle.

• Example:

  • Preference for sweet, fatty, and salty foods among humans.

Sexual Selection

• Definition:

  • A process through which organisms develop characteristics that enhance their reproductive success.

• Darwin's Observations:

  • Darwin found phenomena such as a peacock's tail aesthetically displeasing, yet it played a role in sexual selection.

• Mechanisms Proposed by Darwin:

  1. Intrasexual Selection (Same-sex competition)

     • Organisms of the same sex compete for the mating interest of the opposite sex.

     • Those with traits favorable for winning mating battles are more successful in reproduction.

     • Example: Aerial hover display of the male bronzed cowbird.

  2. Intersexual Selection (Female/Male choice)

     • Members of one sex prefer mates with specific, desirable characteristics.

     • Traits that attract the opposite sex become more common over generations.

     • Example: The brilliant plumage of the male peacock.

Evolutionary Psychology and Personality

• Evolutionary Psychologists' View:

  • Psychological processes are seen as products of natural and sexual selection; adaptations to ancestral survival and reproductive challenges.

• Focus Areas:

  • A significant emphasis on sex differences in personality, stemming from reproductive capacity and parental investment differences.

Reproductive Capacity and Parental Investment

• Reproductive Capacity:

  • Males: Can have a high number of offspring (max recorded: 900).

  • Females: Limited to about 8-12 offspring across their lifespan.

• Minimal Parental Investment:

  • Females invest more significantly in offspring (e.g., pregnancy, lactation).

  • Males mainly engage in mating.

Hypothesis on Mate Preferences

• Hypothesis A:

  • Differences in reproductive capacity and parental investment lead to sex differences in mate preferences:

    • Males value physical appearance more.

    • Females value resource potential more.

• Supporting Evidence:

  • Study showing differences in ratings of desirable traits in prospective mates.

Sociosexuality

• Hypothesis B:

  • Differences in sexual behavior and willingness to engage in uncommitted sexual contact stem from evolutionary pressures.

  • Males tend to score higher in sociosexuality than females, being more open to multiple partners.

• Research Evidence:

  • Studies by Clark and Hatfield showcasing response differences in dating and sexual propositions.

  • Participants indicated desired number of sexual partners over life span, showing significant differences based on gender.

Criticisms of Evolutionary Psychology

• Common Critiques:

  • Concepts in evolutionary psychology are considered unfalsifiable or controversial.

  • Criticisms include societal implications such as the Cinderella effect, fears of promoting heteronormative and heterosexist views.

• Overall Impact:

  • Evolutionary theories have greatly influenced psychological theory despite noted criticisms.