Sexual Selection and Attraction Theories

Sexual Selection

• Sexual selection is the selection of genes that enhance mating success, distinct from natural selection (which enhances survival).
• Two types of sexual selection:
  • Intrasexual selection: Competition between members of the same sex for access to the opposite sex.
  • Intersexual selection: Choice of members of the opposite sex.

Parasite Theory

• Parasites cause more mortality than other factors.
• Females may prefer males with traits signaling a strong immune response, such as parasite resistance.
• Examples: The length and symmetry of barn swallow tail streamers indicate parasite load and immune function, and females prefer longer tails.

Averageness Hypothesis

• Average or composite faces are often perceived as more attractive than individual faces.
• This may be because average faces are associated with less genetic risk.

Parental Investment Theory

• Parental investment is the investment in offspring by a parent that boosts offspring survival and reproductive success.
• It comes at the cost of investment in other offspring.
• Mating and rearing investment components include time and energy, gametes (sex cells).
• Eggs are significantly larger than sperm, resulting in females typically investing more.
• Females are typically more selective in mate choice because they invest more in offspring.
• Males compete more for mates in species where males invest significantly, and vice-versa.

Mate Preferences - Evolutionary Approach

• Studies (e.g., Buss, 1989) have shown cross-cultural support for sex differences in mate preferences.
• Males often prioritize reproductive capacity in mates, while females emphasize resource acquisition.

Problems with Evolutionary Psychology (EP) Approach

• Significant intra-individual variation in mate preferences exists.
• Biases in sample selection are common.
• Social desirability biases influence responses.
• Other fields (e.g., social psychology) also provide insights into behavior.

Mate Preferences - Face and Odour Preferences

• Preferences for masculine traits in faces are complex across cultures.
• MHC (Major Histocompatibility Complex) genes control immune responses and pathogen resistance.
• In many species, mate choice is affected by olfactory cues, favoring MHC dissimilarity.
• In humans, ovulating women sometimes prefer the scent of MHC-dissimilar men, which is reversed if on contraceptive medication.

Social Roles and Evolutionary vs Social Psychology

• Evolutionary psychology emphasizes evolutionary adaptations influencing psychological sex differences, while social psychology argues social structure influences psychological sex differences.
• Social structure and culture impact the specific mating behaviors.
• Individuals prefer mates who are successful within their social roles.

Gender Equality and Mate Preferences

• Studies suggest that differences in mate preferences between genders decline as gender parity increases.
• Evolutionary Psychology (EP): suggests sex differences in mate preferences stem from gamete size and parental investment.
• Social Psychology (SP): considers gendered social roles as the primary driver of sex differences.

Explore the intriguing concepts of sexual selection and various theories of attraction in this quiz. Understand intrasexual and intersexual selection, the impact of parasites on mate choice, and the reasons behind the attractiveness of average faces. Test your knowledge on how parental investment influences sexual selection.