Human Mating and Evolutionary Psychology: Study Notes

Mating and Evolutionary Psychology

Darwinian Aesthetics

Darwinian aesthetics explores why humans find certain things beautiful, linking perceptions of beauty to evolutionary advantages in our ancestral environment.

• Definition of Beauty: In evolutionary terms, beauty often signals health, fertility, or environmental cues beneficial for survival (e.g., lush plants indicating food and shelter).

• Environmental Preferences: Our preference for lawns and greenery may reflect ancestral environments that provided resources and safety.

• Health Benefits: Exposure to nature reduces stress and aggression, improves health, and encourages physical activity.

• Example: The human attraction to flowers and landscapes may stem from their association with food sources and safe habitats in the Environment of Evolutionary Adaptedness (EEA).

• Additional info: The EEA refers to the environment in which a species evolved and to which it is adapted.

Human Mating: Sex Differences and Evolutionary Pressures

Human mating behavior is shaped by evolutionary pressures, with differences both within and between sexes.

• Intrasexual Differences: Variations within the same sex (e.g., among men or among women).

• Intersexual Differences: Variations between sexes, emphasized in evolutionary psychology due to differences in parental investment and reproductive strategies.

• Key Factors: Parental investment, reproductive success (number of children), and reproductive potential (future number of children possible).

Parental Investment Theory

Trivers' Parental Investment Theory (1972)

This theory explains sex differences in mating behavior based on the relative investment each parent makes in offspring.

• Definition: Parental investment is any effort by a parent that increases offspring survival at the cost of the parent's ability to invest in other offspring.

• Gamete Differences: Females produce a small number of large, resource-rich ova (~430 in a lifetime), while males produce vast numbers of small sperm.

• Female Investment: Includes gestation, lactation, and post-partum care, leading to greater selectivity in mate choice.

• Male Investment: Typically lower, leading to less choosiness and more competition for mates.

• Example: In most mammals, females are choosier about mates due to higher investment in offspring.

Handicap Principle

The handicap principle suggests that some traits are costly to maintain but serve as honest signals of genetic quality.

• Definition: Costly traits (e.g., peacock's train) indicate an individual's ability to survive despite the handicap, signaling good genes to potential mates.

• Purpose: Allows assessment of survival ability and honest signaling of gene quality.

• Example: Bright plumage in birds or elaborate human displays (e.g., conspicuous consumption) may serve as handicaps.

Reproductive Value and Fertility

Reproductive Value

Reproductive value refers to the expected future reproductive output of an individual at a given age and sex.

• Definition: The number of children a person is likely to have in the future.

• Sex Differences: Men tend to prefer younger women due to higher reproductive value (longer window for reproduction).

• Fertility vs. Reproductive Value: Fertility is the likelihood of producing offspring from a given mating, while reproductive value is the potential for future reproduction.

• Human Females: Unlike other great apes, human females do not show obvious signs of fertility (concealed ovulation).

• Example: Human breast size may signal constant fertility, unlike other primates where breast swelling signals ovulation.

Paternity Certainty

Challenges and Implications

Paternity certainty refers to the degree of confidence a male has that he is the biological father of his mate's offspring.

• Female Certainty: Women are always certain of maternity due to direct involvement in gestation and birth.

• Male Uncertainty: Men face uncertainty due to concealed ovulation, potential for extra-pair copulations, and separation from the birth event.

• Behavioral Implications: Men may seek signs of sexual exclusivity, while women may seek signs of emotional loyalty.

• Parental Investment: Paternal care improves child survival, so mothers may encourage paternal investment.

• Example: Jealousy and mate-guarding behaviors are more pronounced in men due to paternity uncertainty.

Mating Systems

Types of Mating Systems

Mating systems describe the patterns of sexual relationships and parental investment in a species.

• Polygamy: Individuals mate with more than one partner. Two main forms:

  • Polygyny: One male mates with multiple females (most common in mammals).

  • Polyandry: One female mates with multiple males (rare; e.g., some Tibetan societies).

• Monogamy: Individuals mate with one partner. Rare in mammals but considered ideal in humans.

• Sexual Dimorphism: Systematic physical differences between sexes; greater dimorphism often indicates polygynous systems.

• Human Dimorphism: Humans are less dimorphic than most mammals, suggesting a tendency toward monogamy or slight polygyny.

• Example: In the USA, average male and female body weights overlap significantly, indicating moderate dimorphism.

Mating System	Description	Prevalence in Mammals
Monogamy	One male, one female	Rare
Polygyny	One male, multiple females	Common
Polyandry	One female, multiple males	Very rare

Mate Preferences

Universal and Sex-Differentiated Preferences

Research shows both universal and sex-specific mate preferences across cultures.

• Universal Preferences: Both sexes value intelligence, kindness, honesty, health, and shared values.

• Sex Differences: Women prioritize resources, industriousness, and ambition; men prioritize physical attractiveness.

• Buss (1989) Study: Surveyed 37 cultures, finding consistent sex differences in mate preferences.

• Example: Wealthy men often marry attractive women; women prefer men with resources and ambition.

Trait	Importance to Women	Importance to Men
Financial Resources	High	Lower
Physical Attractiveness	Lower	High
Kindness/Honesty	High	High

Preferences for Attractiveness

• Youthfulness: Features such as large eyes, smooth skin, and small jaw signal high reproductive value (youth).

• Neoteny: The retention of juvenile features in adults, considered attractive as it signals youth and fertility.

• Hormonally Mature Features: Pronounced cheekbones, low waist-to-hip ratio, clear skin, shiny hair, and good teeth signal health and fecundity.

Short-Term vs. Long-Term Mating Preferences

Differences in Mate Selection Strategies

Humans may pursue different strategies depending on whether they seek short-term or long-term mates.

• Long-Term Mates: Commitment, shared parenting, emotional connection, and exclusivity are prioritized.

• Short-Term Mates: Physical attractiveness and genetic quality are prioritized; less concern for personality or long-term compatibility.

• Sex Differences: Women are choosier about short-term mates, especially during fertile periods; men are generally less selective for short-term relationships.

• Example: Women may prefer more masculine men for short-term relationships during ovulation but seek personality compatibility for long-term partners.

Major Issues in Mate Preference Research

Methodological Considerations

• Survey Data: Much of the research relies on self-reported preferences, which may not always reflect actual behavior.

• Mate Value: An individual's own desirability as a mate influences their preferences and choices.

• Additional info: Mate value can include physical attractiveness, resources, social status, and personality traits.