Evolutionary explanations

• Sexual selection: An evolutionary explanation of partner preference. Behaviors that increase reproductive success are passed on and may become exaggerated over further generations.
• Human reproductive behavior: Refers to any behaviors which relate to opportunities to reproduce and thereby increase the survival chances of our genes, includes partner preferences such as mate choice and mate competition.
• Parental investment: The amount each parent invests into the child.
• Sexual selection explains why some characteristics that may appear to be more disadvantageous may offer an advantage in human reproductive behavior because they are attractive to potential mates. These include genetic (e.g. physical characteristics) and adaptive (e.g. aggressiveness)
• Anisogamy: Refers to the differences between male and female sex cells (gametes). Sperm are small and produced in large quantities, eggs are large with few being produced.
• Anisogamy also affects partner preference because it gives rise to two difference mating strategies, meaning there is two types of sexual selection.
• Types of sexual selection: Inter-sexual selection and Intra-sexual selection.
• Inter-sexual selection: This is between the sexes, the strategies that males use to select females.
• Intra-sexual selection: This is within the sex, such as the strategies between males to be the one that is selected.
• Trivers (1972): Females make a greater investment of time to having off-spring, therefore females are more choosy and they decide on a partner who is more genetically fit who can protect them. (Inter-sexual selection)
• Runaway process: Female preference determines which features are passed on. E.g. if height is considered attractive then over generations males will become taller because they are the only ones who find a mate. (Inter-sexual selection)
• Fisher (1930): Developed sexy son hypothesis. This is when a female mates with a male who has desirable characteristics, this 'sexy' trait is inherited by her son, this increases the lightly hood that successive generations of females will mate with the offspring.
• Intra-sexual selection refers to competition between people of the same sex for mates, the winner passes on their characteristics to their offspring.
• Dimorphism: Obvious differences between males and females. For example, in physical competition between males ,size matters, larger males have an advantage. This doesn't apply to females so there was no evolutionary drive for females to be larger, therefore it creates differences in genders.
• Men are more likely to want casual sex because women are more at risk of wasting nine months for a child after sex.
• The characteristics that are favoured and passed on are those that allow a man to compete with his rivals. For example, males benefit from being aggressive to get women which leads to aggressive men. This is controversial as it causes a rise in perceived negative characteristics.
• Evaluation- Research support for intra-sexual selection:

  Buss carried out a survey which asked over 10,000 adults in 33 countries which attributes they look for in a partner preference.

  He found that females placed more value on resource characteristics whereas men placed more value on youthfulness and attractiveness.

  These findings reflect sex differences in partner preferences and support the sexual selection theory.
• Evaluation- Research support for inter-sexual selection:

  • Clark and Hatfield conducted a study to investigate the difference in reproductive behaviour between men and women.
  • An actor/actress asked multiple people from the opposite gender if they would want sex with them that night.
  • They found no female agreed but 75% of males agreed.
  • This supports the view that females are much choosier when it comes to selecting sexual partners.
• Evaluation- Inter-sexual selection:

  • Buss and Schmitt argue that both males and females adopt similar mating strategies when seeking long term relationships, both are choosy.
  • Its more complex than before.
• Evaluation- Ignores social and cultural influences:

  • Partner preferences have been influenced by rapidly changing social norms.
  • For example women are no longer reliant on men to provide for them.
  • Bereczkei argues that this social change has consequences for women's mate preference which may longer not be resource orientated.
  • Chang found that in China some partner prefrences had changed and some hadn't, which corresponding with changes at the time.
  • Mate preferences are an outcome of evolutionary and cultural influences.
• Evaluation- Support from lonely hearts research:

  • Wayneforth and Dunbar found that in the lonely heart newspapers women described themselves as youthful and attractive whereas men described themselves as successful.
  • This supports the idea that women look for resourceful men and men look for youthful women.
• Evaluation- Support from waist the hip ratio:

  • Singh found that as long as a women's hip to waist ratio is about 0.7 then men find the woman attractive.
  • The combination of smaller waist to wider hips gives men the impression of an 'honest signal' that the woman isn't currently pregnant.
  • Shows that men still care about creating their own offspring.